Prosthetic knee with a rectification hydraulic system

ABSTRACT

Described here are prosthetic systems, devices, and methods of use therefor. Generally, a prosthesis may be configured to set a resistance to rotation of a prosthetic joint based on a phase of gait. The prosthesis may include a first cylinder, a first piston slidable within the first cylinder, a fluid sump, and a fluid circuit. The fluid circuit may include a plurality of interconnected fluid channels having a unidirectional variable-resistance valve and a set of check valves that are configured to provide unidirectional flow through the valve during piston compression and extension.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application in a continuation of U.S. patent application Ser. No.16/489,673, filed Aug. 28, 2019, entitled “PROSTHETIC KNEE WITH ARECTIFICATION HYDRAULIC SYSTEM” which claims priority to PCT/US18/20748,filed Mar. 2, 2018, which claims priority to U.S. ProvisionalApplication Ser. No. 62/466,305, filed on Mar. 2, 2017, the contents ofeach are hereby incorporated by reference in their entirety.

FIELD

Systems and methods herein relate to prosthetics with a hydraulicdamping system, including but not limited to prosthetic knees andankles.

BACKGROUND

Prosthetic limbs are designed to substitute for a body part that may bemissing due to trauma, disease, or congenital conditions. Thedevelopment of prosthetics such as a prosthetic knee with a more naturalgait or function is an ongoing endeavor. Some prosthetic knees include ahydraulic system to control rotation of a rotor coupled to a shank abouta knee joint. Some hydraulic systems include a hydraulic cylinder,piston, hydraulic fluid, and a hydraulic circuit having hydraulic fluidchannels and valves for controlling a resistance of the hydraulic fluidflowing through the hydraulic system. A range of motion of theprosthetic joint may thus be controlled to mimic natural gait. However,hydraulic systems need to be capable of fast response times in order totransition the prosthetic joint to different levels of resistance whentransitioning between stance phase and swing phase movement. The sizeand complexity of the hydraulic systems also affects the performance andcost of the prosthetics. Therefore, additional prosthetic devices may bedesirable.

SUMMARY

Described herein are prosthetic joint systems and methods. A lower limbprosthesis such as a prosthetic knee may be coupled to a hydraulicdamping system and be configured to set a resistance of the prostheticknee joint based on a phase of gait. In order to increase user safety,the hydraulic systems should function in a predictable manner underconditions such as an unexpected loss of power. The prosthesis mayinclude a first cylinder, a first piston slidable within the firstcylinder, a fluid sump, and a fluid circuit. The fluid circuit mayinclude a plurality of intersecting or interconnected fluid channels orpaths having a unidirectional variable-resistance valve and a set ofcheck valves that may be configured to permit unidirectional flowthrough the valve during piston compression and extension, or duringflexion and extension of the prosthesis.

In one example, a prosthesis is provided, comprising a first cylinderwith a first cylinder port and a second cylinder port, a first pistonslidable within the first cylinder, a fluid sump comprising a sump port,and a fluid circuit. The fluid circuit may comprise a first fluidchannel comprising a first channel inlet, a first channel outlet, and aunidirectional variable-resistance valve configured to set a variableresistance to flow through the first fluid channel, a second fluidchannel comprising a second channel inlet, a second channel outlet, anda second channel check valve. A third fluid channel may comprise a thirdchannel inlet, a third channel outlet and a third channel check valve. Afourth fluid channel may comprise a fourth channel inlet, a fourthchannel outlet, and a fourth channel check valve. A fifth fluid channelmay comprise a fifth channel inlet, a fifth channel outlet and a fifthchannel check valve. A first intersection (e.g., interconnection) maycomprise the first channel inlet, the second channel outlet, and thefifth channel outlet. A second intersection may comprise the firstcylinder port, the second channel inlet and the third channel outlet. A.third intersection may comprise the sump port, the third channel inletand the fourth channel inlet. A fourth intersection may comprise thesecond cylinder port, the fourth channel outlet and the fifth channelinlet. A hydraulic assembly comprising the above components may also beprovided for use with a limb prosthesis, orthotic, assistive device, orrobotic linkage.

The prosthesis or hydraulic assembly may further comprise a flexionstate during cylinder compression wherein the fluid circuit may beconfigured to permit fluid flow along a first fluid path sequentiallythrough the second cylinder port, the fifth channel check valve, thevariable-resistance valve, the third channel check valve, and to thefirst cylinder port. The flexion state may also be further configured topermit fluid flow in a second fluid path from the variable-resistancevalve and to the sump port, and optionally to resist fluid flow throughthe second channel check valve and the fourth channel check valve. Theflexion state may be configured to permit fluid flow simultaneously inthe first and second fluid paths. The prosthesis may further comprise anextension state during cylinder extension wherein the fluid circuit isconfigured to permit fluid flow along a third fluid path sequentiallythrough the first cylinder port, the second channel check valve, thevariable-resistance valve, the fourth channel check valve, and to thesecond cylinder port. The extension state may be further configured topermit fluid flow along a fourth fluid path sequentially from the sumpport and to the fourth channel check valve, and may be furtherconfigured to resist fluid flow through the second channel check valveand the fourth channel check valve, and/or configured to permit fluidflow simultaneously in the third and fourth fluid paths. The prosthesismay include a mechanical sensor, wherein a resistance of thevariable-resistance valve may be determined based upon input from themechanical sensor. The variable-resistance valve may be selected fromthe group consisting of a solenoid valve, a spool valve, and a voicecoil valve.

The fluid circuit may further comprise a three-way valve, which maycomprise a first valve port connected to the fluid sump at a second sumpport, a second valve port connected to the second intersection, and athird valve port connected to the fourth intersection. The prosthesis orfluid circuit may further comprise a variable resistor located betweenthe third valve port and the fourth intersection along a sixth fluidchannel. The sixth fluid channel may comprise a sixth channel inlet atthe fourth intersection and a sixth channel outlet connected to thethird valve port. The variable resistor may be user adjustable, with adynamic or static setting. The variable resistor may be a unidirectionalvariable resistor configured to permit flow from the fourth intersectionto the third valve port.

The three-way valve may be a normally open three-way valve, and in somefurther examples, may be configured to permit fluid passage between thefirst, second, and third valve ports when open, and to block fluidpassage between the first, second, and third valve ports when closed.The variable resistor may be configured to block fluid flow from thethird valve port to the fourth intersection regardless of whether thethree-way valve is open or closed. The prosthesis may further comprise apower-off flexion state during cylinder compression wherein the fluidcircuit is configured to permit fluid flow along a fifth fluid pathsequentially through the second cylinder port, the variable resistor,the third valve port, the second valve port, and to the first cylinderport. The fluid circuit of the power-off flexion state may be furtherconfigured to permit a fluid flow along a sixth fluid path from thefirst valve port to the fluid sump. The prosthesis may further comprisea power-off extension state wherein the fluid circuit may be configuredto permit fluid flow along a seventh fluid path sequentially through thefirst cylinder port, the second valve port, the first valve port, thefirst sump port, the fourth fluid channel, and to the second cylinderport. In some further examples, the variable resistance valve in thefirst fluid channel may be a three-way spool valve and further comprisea secondary channel inlet.

The fluid circuit may also further comprise a seventh fluid channelcomprising a seventh channel inlet, a seventh channel outlet, and aseventh channel check valve, wherein the seventh channel inlet may beconnected to the first cylinder port or the second intersection. Aneighth fluid channel may comprise an eighth channel inlet, an eighthchannel outlet, and a variable resistor. A fifth intersection maycomprise the seventh fluid channel outlet, the eighth channel outlet andthe secondary inlet of the three-way spool valve, wherein the firstintersection further comprises the eighth channel inlet. The prosthesismay also further comprise a power-off flexion state during cylindercompression wherein the fluid circuit may be configured to permit fluidflow along an eighth fluid path sequentially through the second cylinderport, the fifth fluid channel, the eighth fluid channel, the secondinlet of the variable resistance valve, the third fluid channel, and tothe first cylinder port. The fluid circuit of the power-off flexionstate may be further configured to permit a fluid flow from the firstchannel outlet to the fluid sump.

The prosthesis or hydraulic assembly may also further comprise apower-off extension state during cylinder extension wherein the fluidcircuit may be configured to permit fluid flow along a ninth fluid pathsequentially through the first cylinder port, the seventh fluid channel,the first second inlet of the variable resistance valve, the fourthfluid channel, and to the second cylinder port. The power-off extensionstate may be further configured to permit a fluid flow from the fluidsump to the fourth fluid channel. The three-way spool valve may comprisea spring and may be configured to normally permit fluid communicationbetween the secondary inlet and the first channel outlet when thethree-way spool valve is not powered. The fluid sump may also comprise aspring-biased piston or a pneumatic piston. The prosthesis may alsofurther comprise an upper joint member coupled to the first piston, anda lower joint member coupled to the upper joint member and the firstcylinder. The prosthesis may be a prosthetic knee or a prosthetic ankle.The prosthesis may also further comprise a load cell disposed on atleast one of the first cylinder and the first piston.

In still other examples, methods of using the hydraulic assembly orprosthesis above are provided, comprising transmitting hydraulic fluidin the fluid circuit as indicated during the flexion state duringprosthesis flexion and when the prosthesis variable resistance valve ispowered, and transmitting hydraulic fluid in the fluid circuit asindicated during the extension state during prosthesis extension andwhen the prosthesis variable resistance valve is powered. Another methodof using the hydraulic assembly or prosthesis may comprise transmittinghydraulic fluid in the fluid circuit as indicated during the flexionstate during prosthesis flexion and when the prosthesis variableresistance valve is powered, transmitting hydraulic fluid in the fluidcircuit as indicated during the extension state during prosthesisextension and when the prosthesis variable resistance valve is powered,and transmitting hydraulic fluid in the fluid circuit as indicatedduring the power-off flexion state during prosthesis flexion and whenthe prosthesis variable resistance valve is not powered. Still anothermethod of using the hydraulic assembly or prosthesis may comprisetransmitting hydraulic fluid in the fluid circuit as indicated duringthe flexion state during prosthesis flexion and when the prosthesisvariable resistance valve is powered, transmitting hydraulic fluid inthe fluid circuit as indicated during the extension state duringprosthesis extension and when the prosthesis variable resistance valveis powered, transmitting hydraulic fluid in the fluid circuit asindicated during the power-off flexion state during prosthesis flexionand when the prosthesis variable resistance valve is not powered, andtransmitting hydraulic fluid in the fluid circuit as indicated duringthe power-off extension state during prosthesis extension and when theprosthesis variable resistance valve is not powered.

In another example, a fluid circuit is provided, comprising a firstfluid channel comprising a first channel inlet, a first channel outlet,and a unidirectional variable-resistance valve configured to set avariable resistance to flow through the first fluid channel. A secondfluid channel may comprise a second channel inlet, a second channeloutlet, and a second channel check valve. A third fluid channel maycomprise a third channel inlet, a third channel outlet and a thirdchannel check valve. A fourth fluid channel may comprise a fourthchannel inlet, a fourth channel outlet, and a fourth channel checkvalve. A fifth fluid channel may comprise a fifth channel inlet, a fifthchannel outlet, and a fifth channel check valve. A first intersection(e.g., interconnection) may comprise the first channel inlet, the secondchannel outlet, and the fifth channel outlet. A second intersection maycomprise a first bi-directional channel, the second channel inlet, andthe third channel outlet. A third intersection may comprise a secondbi-directional channel, the third channel inlet, and the fourth channelinlet. A fourth intersection may comprise a third bi-directionalchannel, the fourth channel outlet and the fifth channel outlet. Thefluid circuit may further comprise a first state wherein the fluidcircuit is configured to permit fluid flow along a first fluid pathsequentially through the third bidirectional channel, the fifth channelcheck valve, the variable-resistance valve, the third channel checkvalve, and to the first directional channel. The first state may befurther configured to permit fluid flow in a second fluid path from thevariable-resistance valve and to the second bi-directional channel, andmay be further configured to resist fluid flow through the secondchannel check valve and the fourth channel check valve. The first statemay be configured to permit fluid flow simultaneously along the firstand second fluid paths.

The fluid circuit may further comprise a second state wherein the fluidcircuit may be configured to permit fluid flow along a third fluid pathsequentially through the first bidirectional channel, the second channelcheck valve, the variable-resistance valve, the fourth channel checkvalve, and to the third bi-directional channel. The second state may befurther configured to permit fluid flow along a fourth fluid pathsequentially from the second bidirectional channel and to the fourthchannel check valve. The second state may be further configured toresist fluid flow through the second channel check valve and the fourthchannel check valve. The second state may be configured to permit fluidflow simultaneously in the third and fourth fluid paths. The fluidcircuit may further comprise a mechanical sensor and a resistance of thevariable-resistance valve may be determined based upon input from themechanical sensor. The variable-resistance valve may be selected fromthe group consisting of a solenoid valve, a spool valve and a voice coilvalve. The fluid circuit may further comprise a three-way valve,comprising a first valve port connected to the second bi-directionalchannel, a second valve port connected to the second intersection, and athird valve port connected to the fourth intersection. The fluid circuitmay further comprise a variable resistor located between the third valveport and the fourth intersection along a sixth fluid channel, the sixthfluid channel may comprise a sixth channel inlet at the fourthintersection and a sixth channel outlet connected to the third valveport. The variable resistor is a unidirectional variable resistorconfigured to permit flow from the fourth intersection to the thirdvalve port. The variable resistor may be user adjustable, with a dynamicor static setting. The three-way valve may be a normally open three-wayvalve. The three-way valve may be configured to permit fluid passagebetween the first, second, and third valve ports when open, and to blockfluid passage between the first, second, and third valve ports whenclosed. The variable resistor may be configured to block fluid flow fromthe third valve port to the fourth intersection regardless of whetherthe three-way valve is open or closed.

The fluid circuit may further comprise a third state wherein the fluidcircuit may be configured to permit fluid flow along a fifth fluid pathsequentially through the third bidirectional channel, the variableresistor, the third valve port, the second valve port, and to the firstbi-directional channel. The third state of the fluid circuit may befurther configured to permit a fluid flow along a sixth fluid path fromthe first valve port to the second bi-directional channel. The fluidcircuit may further comprise a power-off extension state wherein thefluid circuit may be configured to permit fluid flow along a seventhfluid path sequentially through the first cylinder port, the secondvalve port, the first valve port, the first sump port, the fourth fluidchannel, and to the second cylinder port. The variable resistance valvemay be a three-way spool valve and further comprise a secondary channelinlet. The fluid circuit may further comprise a seventh fluid channelcomprising a seventh channel inlet, a seventh channel outlet, and aseventh channel check valve, wherein the seventh channel inlet isconnected to the first bidirectional channel or the second intersection.An eighth fluid channel may comprise an eighth channel inlet, an eighthchannel outlet, and a variable resistor, and a fifth intersection of theseventh fluid channel outlet, the eighth channel outlet and thesecondary inlet of the three-way spool valve. The first intersection mayfurther comprise the eighth channel inlet. The fluid circuit may furthercomprise a third state wherein the fluid circuit may be configured topermit fluid flow along an eighth fluid path sequentially through thethird bi-directional channel, the fifth fluid channel, the eighth fluidchannel, the secondary channel inlet of the variable resistance valve,the third fluid channel, and to the first bi-directional channel. Thethird state of the fluid circuit may be further configured to permit afluid flow from the first channel outlet to the second bi-directionalchannel.

The fluid circuit may further comprise a fourth state wherein the fluidcircuit may be configured to permit fluid flow along a ninth fluid pathsequentially through the first bidirectional channel, the seventh fluidchannel, the first second inlet of the variable resistance valve, thefourth fluid channel, and to the third bi-directional channel. Thefourth state may be further configured to permit a fluid flow from thesecond bi-directional channel to the fourth fluid channel. The three-wayspool valve may comprise a spring and may be configured to normallypermit fluid communication between the secondary inlet and the firstchannel outlet when the three-way spool valve is not powered. The fluidcircuit may further comprise a cylinder comprising a first variablevolume chamber, a second variable volume chamber, and a slidable pistontherebetween, wherein the first bi-directional channel coupled to thefirst variable volume chamber and the third bi-directional channel iscoupled to the second variable volume chamber. The fluid circuit mayalso further comprise a fluid sump connected to the second bidirectionalfluid channel.

In another example, a hydraulic assembly or prosthetic assembly isprovided, comprising a first cylinder comprising a first variable volumecavity, a second variable volume cavity, a piston therebetween, a pistonshaft coupled to the piston and slidably extending out of the firstvariable volume cavity, first cylinder port to the first variable volumecavity, and a second cylinder port to the second variable volume cavity.A fluid circuit may comprise a first unidirectional fluid pathcontaining a proportional valve, a second unidirectional fluid path fromthe first cylinder port to the first unidirectional fluid path, a thirdunidirectional fluid path from the first unidirectional fluid path tothe first cylinder port, a fourth unidirectional fluid path from thefirst unidirectional fluid path to the second cylinder port, and a fifthunidirectional fluid path from the second cylinder port to the firstunidirectional fluid path. The hydraulic assembly or prosthetic assemblymay further comprise a fluid sump coupled to the first unidirectionalfluid path and the fourth unidirectional fluid path, and/or a three-wayvalve with a first valve port connected to the fluid sump, a secondvalve port connected to the first cylinder port, and a third valve portconnected to the second cylinder port. The hydraulic assembly orprosthetic assembly may also further comprise a user-adjustable variableresistor between the third valve port and the second cylinder port. Thethree-way valve may be normally open. The proportional valve may be athree-way proportional valve and may comprise a secondary channel inlet.The fluid circuit may further comprise a sixth unidirectional fluid pathfrom the fifth unidirectional fluid path to the secondary inlet of theproportional valve, and a seventh unidirectional fluid path from thefirst cylinder port to the secondary inlet of the proportional valve.The sixth unidirectional fluid path may include a user-adjustablevariable resistor. The prosthetic assembly may also further comprise asensor, and a controller connected to the sensor and to the proportionalvalve, wherein the sensor may be configured to adjust the resistancethrough the proportional valve based upon the sensor.

The first cylinder may define a longitudinal axis. The fluid circuit maybe parallel to the first cylinder and laterally offset from thelongitudinal axis. The fluid sump may be parallel and in-line with thefluid circuit.

In another example, a hydraulic assembly or prosthetic is provided,comprising a first cylinder defining a longitudinal axis. The firstcylinder may comprise a first cylinder port and a second cylinder port.A first piston may be slidable within the first cylinder. A fluidcircuit may be parallel to the first cylinder and laterally offset fromthe longitudinal axis. The fluid circuit may comprise a set of fluidchannels and a variable-resistance valve configured to set a variableresistance to flow through the set of fluid channels. A fluid sump maybe parallel and in-line with the fluid circuit. The fluid sump maycomprise a sump port. The fluid circuit and the fluid sump may beattached to the first cylinder along a length of the first cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B are schematic side views of a variation of a prostheticknee.

FIGS. 2A-2D are illustrative exterior views of an exemplary variation ofa prosthetic knee. FIG. 2A is a side view, FIG. 2B is a perspectiveview. FIG. 2C is a rear view, and FIG. 2D is a front view.

FIGS. 3A-3B are illustrative exterior views of an exemplary variation ofa hydraulic system. FIG. 3A is a perspective view and FIG. 3B is a sideview. FIG. 3C is a cross-sectional side view of the hydraulic system inFIGS. 3A-3B.

FIG. 4 is a block diagram of a variation of a prosthetic joint.

FIGS. 5A-5C are illustrative schematic diagrams of a variation of ahydraulic system. FIG. 5A illustrates the system architecture, FIG. 5Billustrates fluid flow for flexion, and FIG. 5C illustrates fluid flowfor extension.

FIGS. 6A-6F are illustrative schematic views of a variation of a controlvalve. FIG. 6A is a cross-sectional side view of a sleeve and spool,FIG. 6B is a side view of the sleeve, and FIGS. 6C-6E arecross-sectional side views of fluid flow using the valve. FIG. 6F is aside view of the sleeve, spool, and orifices.

FIGS. 7A-7E are illustrative schematic diagrams of another variation ofa hydraulic system. FIG. 7A illustrates the system architecture, FIG. 7Billustrates fluid flow for power ON flexion, and FIG. 7C illustratesfluid flow for power ON extension. FIG. 7D illustrates fluid flow forpower OFF flexion and FIG. 7E illustrates fluid flow for power OFFextension.

FIGS. 8A-8F are cross-sectional side views of an exemplary variation ofa control valve. FIG. 8A illustrates a cross-sectional side view of aproportional spool valve and FIG. 8B illustrates a cross-sectional sideview of a power OFF valve. FIG. 8C illustrates a schematic diagram ofthe valve. FIG. 8D illustrates a schematic diagram of the valve forpower OFF flexion. FIG. 8E illustrates a schematic diagram of the valvefor power OFF extension.

FIGS. 9A-9E are illustrative schematic diagrams of yet another variationof a hydraulic system. FIG. 9A illustrates the system architecture. FIG.9B illustrates fluid flow for power ON flexion and FIG. 9C illustratesfluid flow for power ON extension. FIG. 9D illustrates fluid flow forpower OFF flexion and FIG. 9E illustrates fluid flow for power OFFextension.

FIGS. 10A-10D are illustrative schematic views of fluid flow usinganother variation of a control valve.

FIGS. 11A-11E are cross-sectional side views of another exemplaryvariation of a control valve. FIG. 11A illustrates a cross-sectionalside view of a three-port spool valve and FIG. 11B illustrates aschematic diagram of the valve. FIGS. 11C and 11D illustrate schematicdiagrams of the valve for power ON fluid flow. FIG. 11E illustrates aschematic diagram of the valve for power OFF fluid flow.

FIG. 12 is a schematic side view of another variation of a prostheticknee.

FIG. 13A is cross-sectional side view of another variation of a controlvalve.

FIGS. 13B-13E are illustrative schematic views of a variation of thecontrol valve depicted in FIG. 13A. FIG. 13B is a cross-sectional sideview of a sleeve and spool, and FIGS. 13C-13E are side views of thesleeve, spool, and orifice. FIGS. 13F-13I illustrate schematic diagramsof the valve in a respective fully open state, high resistance state,lock out state, and power OFF state.

DETAILED DESCRIPTION

Described herein are hydraulic assemblies, prosthetic systems, andmethods for controlling a hydraulic assembly or prosthesis. A prostheticjoint as described herein may be controlled using a microprocessor toadjust a resistance of the joint based on a phase of gait of the user.In variations where the prosthetic joint includes a hydraulic systemincluding a hydraulic cylinder and piston, the microprocessor may beconfigured to adjust a hydraulic fluid control valve to set a resistanceof hydraulic fluid through the hydraulic system for different phases ofa gait cycle. In some variations, the hydraulic system may includecomponents (e.g., valves, fluid channels) to set a resistance ofhydraulic fluid through the hydraulic system during power loss fordifferent phases of gait.

I. System Prosthetic Knee

Described herein are prosthetics for use by an amputee. In somevariations, the prosthetic joints shown herein may be configured as aprosthetic knee for use by an above-knee amputee. The prosthetic kneemay include a hydraulic system including a hydraulic cylinder coupled toa hydraulic damper. A controller coupled to the hydraulic system may beconfigured to set a resistance to rotation of the knee joint accordingto a phase of gait, thus allowing a user to move with a more naturalgait motion. As described in more detail, the prosthetic joint may beconfigured for use in other locations. For example, the prosthetic jointmay be configured for use as a prosthetic ankle for a below-knee amputeeor an above-knee amputee.

FIGS. 1A-1B illustrate schematic side views of a prosthetic knee (100).The prosthetic knee (100) may include an upper joint member (110)rotatably coupled to a lower joint member (120) about a first joint(112). In some variations, the upper joint member (110) may be a rotor,the lower joint member (120) may be a shank, and the first joint (112)may be a knee joint. The upper joint member (110) and the lower jointmember (120) may move with respect to each other in flexion andextension. In variations where the prosthetic joint is a prostheticankle, an upper and lower joint member may move with respect to eachother in dorsiflexion and plantar flexion. In some variations, the upperjoint member (110) and lower joint member (120) may pivot about a singlepivot, across a different joint such as a ball-and-socket joint, oracross a plurality of points such as in a multi-bar linkage, or othertype of linkage.

The upper joint member (110) and the lower joint member (120) may becoupled to a hydraulic system (160) that is configured to actuate and/ordampen rotation of the upper joint member (110) relative to the lowerjoint member (120). For example, the hydraulic system (160) may beconfigured to set a rotational resistance of the prosthetic knee (100).A hydraulic system (160) may comprise a piston assembly (130) slidablycoupled to a hydraulic cylinder (150). The piston assembly (130) mayinclude a piston (not shown) located within the cylinder (150) and apiston shaft coupled to the piston and extending out of the cylinder(150). Thus, the piston assembly (130) may alternately compress into orextend out of the cylinder (150). FIG. 1A illustrates extension of thepiston assembly (130) while FIG. 1B illustrates compression of thepiston assembly (130). The upper joint member (110) may rotate (116)relative to the lower joint member (120) absent the first joint (112).The piston assembly (130) may be a linear piston while the chamber ofthe hydraulic cylinder (150) may be cylindrical. The piston assembly(130) may be coupled to the upper joint member (110) at a first cylindermount (114). The cylinder (150) may be coupled to the lower joint member(120) at a second cylinder mount (122).

In other examples, the piston assembly (130) may be a rotary piston (notshown) located in a rotary chamber of the cylinder (150), such that thepiston assembly (130) may rotate relative to the upper joint member(110) about an axis of the first cylinder mount (114). The cylinder(150) may rotate relative to the lower joint member (120) about an axisof the second cylinder mount (122).

When torque is applied about the first joint (112), the upper jointmember (110) may rotate (116) about the first joint (112) such that thepiston assembly (130) either compresses into or extends out of thecylinder (150). As the upper joint member (110) and the lower jointmember (120) rotate (116) about the joint (112), the piston assembly(130) may rotate about an axis of the first cylinder mount (114)relative to the upper joint member (110), and the cylinder (150) mayrotate about an axis of the second cylinder mount (122) relative to thelower joint member (120). The piston assembly (130) may be configuredsuch that an internal cavity of the cylinder (150) is separated into twovariable-volume chambers. As the piston assembly (130) moves within thecylinder (150), hydraulic fluid within the cylinder (150) is displacedfrom one chamber into an opposing chamber. The two chambers may befluidly connected by a hydraulic damper that may include one or morehydraulic fluid channels and a hydraulic fluid flow control system asdescribed in more detail herein. For example, the hydraulic damper maybe fluidly connected with the cylinder (150) through two or morecylinder ports. As described in more detail herein, the hydraulic fluidflow control system may include one or more valves, valve actuators, andfluid sumps.

A resistance to rotation of the joint members about the first joint(112) may be varied (e.g., set between a locked state and an open state)using a control valve (described in more detail herein) of the hydrauliccircuit. As the piston assembly (130) moves within the cylinder (150)(e.g., compresses or extends), hydraulic fluid enters the control valve.A controller (e.g., microprocessor including memory) may be configuredto control an area of a fluid opening in the control valve. A change inan area of the opening in the control valve may change a resistance toflow of the hydraulic fluid in the hydraulic system (160). A resistanceto hydraulic fluid flow through the hydraulic system (160) maycorrespond to a resistance to rotation of the prosthetic joint and thusa phase of gait. In some variations, the control valve may include aspool slidably coupled to a sleeve.

The upper joint member (110) may be coupled to a first connector (140)and the lower joint member (120) may be coupled to a second connector(142) In some variations, the first connector (140) may be a proximalpyramid connector and the second connector (142) may be a distal pyramidconnector.

FIGS. 2A-2D illustrates exterior views of an exemplary variation of aprosthetic knee (200). The prosthetic knee (200) may include a firstupper joint member (210) (e.g., rotor) coupled to a lower joint member(220) (e.g., shank) about a first joint (212) (e.g., knee joint). Theupper joint member (210) and the lower joint member (220) may move withrespect to each other in flexion and extension. The upper joint member(210) may be coupled to a piston assembly (230) with a piston and pistonshaft. The piston assembly (230) may be coupled to the upper jointmember (210) at a cylinder mount (214). The piston assembly (230) mayrotate relative to the upper joint member (210) about an axis of thecylinder mount (214). The upper joint member (210) may be coupled to afirst connector (240) (e.g., proximal pyramid) and the lower jointmember (220) may be coupled to a second connector (242) (e.g., distalpyramid). In some variations, the first connector (140) may be aproximal pyramid connector and the second connector (142) may be adistal pyramid connector. For example, the first connector (240) may beconfigured to attach to a socket (not shown), where the socket may beconfigured to attach to a remnant limb of the amputee. The secondconnector (242) may be configured to attach to a prosthetic foot and/orankle (not shown). The prosthesis (200) may also include one or morebuttons 244 or other controls to actuate the power, wirelessconnectivity, battery level display or other features of the prosthesis(200).

FIGS. 3A-3C illustrate an exemplary variation of a hydraulic assembly(300) that may be used in the prosthetic knee (100, 200) depicted inFIGS. 1A-2D. The hydraulic system (300) may include a piston assembly(310) slidably coupled to a hydraulic cylinder (320), with a pistonlocated in the cylinder (320) and piston shaft extending out of thecylinder (320). An end of the piston assembly (310) may include a firstmount (312) and a piston (311). An end of the hydraulic cylinder (320)may include a second mount (322). In some variations, the first mount(310) may rotatably couple to a rotor and the second mount (322) mayrotatably couple to a shank. As described in more detail herein, ahydraulic damper (330) may be coupled to the hydraulic cylinder (320) tocontrol a resistance of hydraulic fluid flow through the cylinder (320).The hydraulic cylinder (320) may include a first variable volume chamberand a second variable volume chamber (not shown). The volume of eachchamber changes as the piston assembly (310) slides within the hydrauliccylinder (320). The volume may be further dependent on the diameter ofthe piston assembly (310) and its travel length. In some variations, avolume of the hydraulic cylinder chamber (i.e., first and secondvariable volume chambers) may be between about 9 ml and about 30 ml. Forexample, the volume of the hydraulic cylinder chamber may be betweenabout 15 ml and about 20 ml.

FIG. 3C is a cross-sectional side view of the hydraulic assembly (300)comprising the piston assembly (310), hydraulic cylinder (320), andhydraulic damper (330). As discussed in more detail herein, the fluidcircuit may further comprise a set of fluid channels coupled to thevalve (332) (e.g., a variable-resistance three-port valve) and beconfigured to set a variable resistance to flow through the set of fluidchannels. The fluid sump (340) (e.g., accumulator) may be coupledin-line with the fluid circuit (e.g., arranged along the samelongitudinal axis). The hydraulic damper (330) may be parallel andattached to a side of the hydraulic cylinder (320) (e.g., laterallyoffset from a longitudinal axis of the hydraulic cylinder (320)). Thehydraulic damper (330) may be attached to the hydraulic cylinder (320)along a length of the cylinder (320). Accordingly, a length of thehydraulic assembly (300) may be shortened and/or made more compact(relative to a hydraulic assembly having a cylinder and damper arrangedin-line with each other) such that a prosthesis using the hydraulicassembly (300) may accommodate a larger patient population.

In some variations, the piston assembly (310) may comprise a diameter ofbetween about 20 mm and about 30 mm, and a length of between about 8 mmand about 30 mm. For example, the diameter may be between about 22 mmand about 27 mm and the length may be between about 10 mm and about 20mm. The hydraulic damper (330) may comprise a fluid circuit includingthe valve (332), valve spool (334), and fluid sump (340). The fluid sump(340) (e.g., accumulator) may comprise a spring (342), sleeve (344), afluid sump piston (348), a seal (346) coupled to the piston (348), and afluid reservoir (not shown). Additionally or alternatively, the fluidsump (340) may comprise a pneumatic element (e.g., using nitrogen gas)to change a reservoir volume of the fluid sump (340). The fluid sump(340) may be used to receive fluid as a result of piston (310)compression and high temperatures.

In some variations, the fluid sump (340) may comprise a diameter ofbetween about 8 mm and about 30 mm, a length of between about 2 mm andabout 60 mm. In some variations, the spring (342) may have anuncompressed length of between about 5 mm and about 120 mm. For example,the spring (342) may have an uncompressed length of between about 30 mmand about 50 mm. In some variations, the spring (342) may have a springrate of between about 0.2 N/mm and about 10 N/mm. For example, thespring (342) may have a spring rate of between about 0.3 N/mm and about1 N/mm. In some variations, the fluid sump piston (348) may comprise adiameter of between about 8 mm and about 30 mm and a length of betweenabout 5 mm and about 40 mm. For example, the fluid sump piston (348) maycomprise a diameter of between about 15 mm and about 25 mm and a lengthof between about 15 mm and about 30 mm. In some variations, the fluidreservoir may comprise a volume of between about 1.0 ml and about 50.0ml. For example, the fluid reservoir may comprise a volume of betweenabout 1.0 ml and about 10.0 ml with a fluid volume of between about 1.0ml and about 3 ml.

As shown in FIG. 3C, the hydraulic cylinder (320) may comprise aslidable piston assembly (310), a first mount (312) coupled to thepiston assembly (310), a second mount (322) coupled to an end of thehydraulic cylinder (320) opposite the first mount (312), and a pistonseal (316) coupled to a piston sleeve (318). The piston assembly (310)may comprise a bumper (324) and one or more bushings (326). For example,a first bushing (326) may be coupled to the piston assembly (310) withinan internal volume of the hydraulic cylinder (320) and a second bushing(not shown) may be disposed on exterior portion of the hydrauliccylinder (320) and the piston assembly (310). A wiper (329) may beslidably coupled to the piston assembly (310) at an end portion of thehydraulic cylinder (320).

FIG. 4 is a block diagram of a variation of a prosthetic joint (400)having a control scheme to automate control of resistance to rotation ofthe prosthetic joint (400) and may be used in any of the prostheticknees (100, 200) described herein. The prosthetic joint (400) mayinclude a hydraulic system (410) used to set the resistance to rotationof the prosthetic joint (400). The hydraulic system (400) may functionas a hydraulic actuator or damper and be configured to control the flowof hydraulic fluid, and thus the rotation of the prosthetic joint (400).The hydraulic system (410) may include a piston (412), a hydrauliccylinder (414), and a hydraulic damper (416) configured to permit,limit, and/or resist movement of hydraulic fluid within the hydraulicsystem (410), and thus permit, limit, and/or resist rotation of theprosthetic joint (400). In some variations, the hydraulic damper (416)may include a hydraulic actuator having a motor that generates hydraulicpressure to drive rotation of the joint (400). The hydraulic actuatormay also be operated as a damper.

In some variations, the hydraulic system (410) may be controlled by acontroller (420) using one or more sensors (430). The controller (420)may include one or more processors (422) and memory (424). The processor(422) may be any suitable processing device configured to run and/orexecute a set of instructions or code and may include one or more dataprocessors, image processors, graphics processing units, physicsprocessing units, digital signal processors, and/or central processingunits. The processor (422) may be, for example, a general purposeprocessor, Field Programmable Gate Array (FPGA), an Application SpecificIntegrated Circuit (ASIC), and/or the like. The processor (422) may beconfigured to run and/or execute application processes and/or othermodules, processes and/or functions associated with the system and/or anetwork associated therewith (not shown). The underlying devicetechnologies may be provided in a variety of component types, e.g.,metal-oxide semiconductor field-effect transistor (MOSFET) technologieslike complementary metal-oxide semiconductor (CMOS), bipolartechnologies like emitter-coupled logic (ECL), polymer technologies(e.g., silicon-conjugated polymer and metal-conjugated polymer-metalstructures), mixed analog and digital, and/or the like.

In some variations, the memory (424) may include a database (not shown)and may be, for example, a random access memory (RAM), a memory buffer,a hard drive, an erasable programmable read-only memory (EPROM), anelectrically erasable read-only memory (EEPROTv1), a read-only memory(ROM), Flash memory, etc. The memory (424) may store instructions tocause the processor (422) to execute modules, processes and/or functionsassociated with the system (400), such as hydraulic fluid control, gaitdetermination, stumble recovery, sensor control, communication, and/oruser settings.

The prosthetic joint (400) may include one or more sensors (430)including, but not limited, to an inertial measurement unit (IMU) (e.g.,discrete integrated circuit), angle position sensor, differentialpressure sensor, torque sensor, load sensor, and temperature sensor.

An IMU may be provided and may be configured to measure linear andangular accelerations along three axes. For example, absolute tilt maybe measured and used to set a mode (e.g., walking, cycling) that thejoint should be in. In some variations, an IMU may be disposed on and/orcoupled to a rotor and/or shank of the prosthetic joint. The IMU maycomprise an accelerometer and/or gyroscope. In some variations, anaccelerometer of the IMU may have a resolution of at least about 4.8cm/s², an accuracy of about ±39 cm/s², and a measurement range betweenabout ±16 g. A gyroscope of the IMU may have a resolution of at leastabout 0.07 degrees/second, an accuracy between about ±3 deg/sec, and ameasurement range between about ±2000 deg/sec.

An angle position sensor may be disposed on and/or coupled to a. rotorand/or shank. The angle position sensor may be configured to classifythe orientation of the knee. The angle may be used to calculate a torqueof the knee. In some variations, the angle position sensor may be a Hallsensor, an optical encoder, or other angle position sensor. In somevariations, the angle sensor may have a resolution of at least about0.025 degrees/count, and accuracy less than about 1 degree, and maymeasure flexion between about 0 degrees and about 135 degrees.

A differential pressure sensor may be configured to measure differentialpressure in the hydraulic system. In some variations, a torque of theknee may be calculated using a differential pressure and knee angle. Insome variations, the differential pressure sensor may be a strain gaugecoupled to a piston and/or cylinder. In some variations, knee torque maybe calculated using an external torque sensor disposed on the proximalconnector, rotor, shank, or combined with a load sensor at the distalend of the prosthetic joint.

In some variations, a load transducer (e.g., a strain gauge) may bedisposed on or in the piston shaft or the connecting elements of thepiston shaft. A load sensor may be configured to measure a load of theprosthetic joint (400). For example, the load sensor may be configuredto measure the deflection of a compliant element. In some variations,the load sensor may be a strain gauge disposed in a distal connectorand/or rotor. Tn some variations, load and/or torque sensors may be usedto determine toe-off thresholds and user loading of the knee. In somevariations, the load sensor may have a resolution of at least about 0.31N/count, an accuracy of less than about 4.5 N, and may measure a loadbetween about 0 N and about 2000 N. In some variations, the torquesensor may have a resolution of at least about 0.025 Nm/count, anaccuracy of less than about 0.125 Nm, and may measure a torque betweenabout 0 N and about 101 Nm.

A temperature sensor may be disposed on or be adjacent to the hydraulicsystem (410) and/or electronic components of the system (e.g.,controller (420), communication interface (440), power supply (450)) toensure safe operation of the prosthetic joint (400).

FIG. 12 is a schematic side view of another variation of a prostheticknee (1200). The prosthetic knee (1200) may include an upper jointmember (1210) rotatably coupled to a lower joint member (1220) about afirst pivot (1212). A hydraulic system (1230) may be pivotally coupledto the upper joint member (1210) at a first mount (1214) and coupled tothe lower joint member (1220) at a second mount (1222). In somevariations, the upper joint member (1210) may comprise a magnet, such asa samarium-cobalt magnet that may be configured to be diametricallypolarized and provide temperature compensation. The prosthetic knee(1200) may comprise a load cell (1250) located in parallel with and at adistal end of the hydraulic system (1230). For example, the load cell(1250) may be located in one or more of the second mount (1222), pistonshaft, and/or cylinder. In some variations, one or more pressure gaugesor sensors located internally in, or in fluid communication with, thecylinder may be used to measure an absolute pressure(s) or thedifferential pressure in the cylinder between its chambers. Thedifferential pressure may be used to calculate a load on the cylinder.Knee torque may be calculated using the measured load on the cylinderand a moment arm of the cylinder. A moment arm of the cylinder may becalculated from a knee angle measurement.

In variations where the prosthesis is a prosthetic ankle, one or moresensors may comprise a force or load sensor, torque sensor, anglesensor, accelerometer, and/or gyroscope. The sensors may be located onthe prosthetic ankle and/or artificial foot. For example, a force orload sensor, a torque sensor, or both, may be located on a shank or aconnector and configured to measure force, torque, or both applied bythe user to the prosthetic ankle and/or artificial foot. As anotherexample, an angle sensor may be located on an ankle shaft of the pivotbetween the shank and the artificial foot to measure a relative anglebetween the shank and the artificial foot. As another example, anaccelerometer, a gyroscope, or both may be located on a foot couplermount or the artificial foot and configured to sense or measure impact,orientation, etc. Similarly, locating an angle sensor between the shankand the artificial foot may allow relative orientation to be classifiedwithout having to classify a relative orientation of other structure,such as a pylon, and without having to locate sensors on a pylon. Insome variations, the system may comprise one or more of the elementsdescribed in U.S. patent application Ser. No. 13/015,423, filed on Jan.27, 2011, and titled “COMPACT AND ROBUST LOAD AND MOMENT SENSOR,” thecontent of which is hereby incorporated by reference in its entirety.

Referring back to FIG. 4, in some variations, the prosthetic joint (400)may comprise a communication interface (440) including a transceiver(not shown). The controller (420) may use the communication interface(440) to wirelessly connect to an external computing device including,but not limited, to a tablet computer, a laptop computer, a desktopcomputer, a smart phone, or the like. Patient data from memory (424) maybe received by communication interface (440) and output to the externaldevice. As another example, the communication interface (440) maycomprise one or more input devices on the prosthetic joint (400)including one or more buttons, knobs, dials, switches, or the like.

The prosthetic joint (400) may include a power supply (e.g., batteries).The hydraulic damper (416), controller (420), sensors (430), andcommunication interface (440) may be coupled to the power supply (450)to receive power. In some variations, the power supply (450) may bedisposed within a housing of the prosthetic joint (400) and/or connectedexternally to the prosthetic joint (400) via, for example, a powercable. As another example, the power supply (450) may be disposed on abackside of the prosthetic joint (400) and coupled to the hydraulicsystem (410).

In some variations, the systems may comprise one or more elementsdescribed in U.S. patent application Ser. No. 14/707,957, filed on May8, 2015, and titled “PROSTHETIC WITH VOICE COIL VALVE,” and/or U.S.patent application Ser. No. 14/466,081, filed on Aug. 22, 2014, andtitled “MICROPROCESSOR CONTROLLED PROSTHETIC ANKLE SYSTEM FOR FOOTWEARAND TERRAIN ADAPTATION,” each of which is hereby incorporated byreference in its entirety.

B. Hydraulic Circuit

In some variations, a hydraulic assembly or system may comprise asingle-ended piston, a double-acting cylinder (e.g., providing variableresistance in both directions) coupled to a fluid circuit having asingle unidirectional control valve. The single unidirectional controlvalve may set resistance to hydraulic fluid flow in both flexion (e.g.,cylinder compressing) and extension (e.g., cylinder extending). Thecontrol valve may be unidirectional in that the fluid circuit ensuresfluid flow in a single direction into the control valve for bothcompression and extension. The hydraulic assemblies described herein maybe provided for use with a limb prosthesis, orthotic, assistive device,or robotic linkage.

FIG. 5A illustrates a hydraulic assembly (500) including a first piston(510), hydraulic cylinder (520), and a hydraulic fluid flow circuit(530). The piston (510) may be slidable within a hydraulic cylinder(520). A piston shaft (512) coupled to the piston (510) may compress orextend the piston (510) into and out of the cylinder (520). The piston(510) may structurally separate the cylinder (520) into a first chamber(522) and an opposing second chamber (524). The first chamber (522) mayinclude a first cylinder port (526) and the second chamber (524) mayinclude a second cylinder port (528). In some variations, the first andsecond cylinder ports (526, 528) may be located on a sidewall of thecylinder (520) on opposite sides of the piston (510). In somevariations, the first cylinder port (526) may be located at a first endof the cylinder (520) while the second cylinder port (528) may belocated at a second end of the cylinder (520) opposite the first end.

The fluid circuit (530) may be coupled to the hydraulic cylinder (520)through the first and second cylinder ports (526, 528) such that thefluid circuit (530) may be configured to control a resistance ofhydraulic fluid through the hydraulic assembly (500). The fluid circuit(530) may include a plurality of hydraulic fluid channels configured tocontrol hydraulic fluid flow between the first chamber (522), the secondchamber (524), and a fluid sump (550). FIG. 5A illustrates the fluidcircuit (530) comprising a plurality of hydraulic fluid channels. Afirst hydraulic fluid channel (531) may comprise a first channel inlet(580) (labeled in FIG. 5B), a first channel outlet (581), and a firstchannel valve (540) configured to set a variable resistance to flowthrough the first fluid channel (531). In some variations, the firstchannel valve (540) may be a unidirectional variable-resistance valve. Asecond fluid channel (532) may comprise a second channel inlet (582)(labeled in FIG. 5C), a second channel outlet (583), and a secondchannel valve (542). A third fluid channel (533) may comprise a thirdchannel inlet (584) (labeled in FIG. 5B), a third channel outlet (585),and a third channel valve (544). A fourth fluid channel (534) maycomprise a fourth channel inlet (586) (labeled in FIG. 5C), a fourthchannel outlet (587), and a fourth channel valve (546). A fifth fluidchannel (535) may comprise a fifth channel inlet (588) (labeled in FIG.5B), a fifth channel outlet (589), and a fifth channel valve (548).

In some variations, a first interconnection (590) (e.g., intersection)may comprise the first channel inlet (580), the second channel outlet(583), and the fifth channel outlet (589). A second interconnection(591) may comprise the first cylinder port (526), the second channelinlet (582), and the third channel outlet (585). A third interconnection(592) may comprise a sump port (556), the third channel inlet (584), andthe fourth channel inlet (586). A fourth interconnection (593) maycomprise the second cylinder port (528), the fourth channel outlet(587), and the fifth channel inlet (588). In some of these variations,the second interconnection (591) may comprise a first bi-directionalchannel. For example, the first bi-directional channel may extend fromthe first cylinder port (526) to the second interconnection (591). Thethird interconnection (592) may comprise a second bi-directionalchannel. For example, the second bidirectional channel may extend fromthe third interconnection (592) to the first sump port (556). The fourthinterconnection (593) may comprise a third bi-directional channel. Forexample, the third bi-directional channel may extend from the fourthinterconnection (593) to the second cylinder port (528).

In some variations, the first channel inlet (580) may be connectedbetween the second channel valve (542) and the fifth channel valve(548). The first cylinder port (526) may be connected between the secondchannel valve (542) and the third channel valve (544). A sump port (556)may be connected between the third channel valve (544) and the fourthchannel valve (546). The second cylinder port (528) may be connectedbetween the fourth channel valve (546) and the fifth channel valve(548). The second channel valve (542) and fifth channel valve (548) maybe connected in series. The third channel valve (544) and fourth channelvalve 546) may be connected in series. The second channel valve (542)and the third channel valve (544) may be connected in parallel. Thefourth channel valve (546) and the fifth channel valve (548) may beconnected in parallel. A first channel inlet (580) of the firsthydraulic fluid channel (531) may be connected between the second andfifth fluid channels (532, 535). A first channel outlet (581) of thefirst hydraulic fluid channel (531) may be connected between the thirdand fourth fluid channels (533, 534).

The first valve (540) may be configured to set a resistance to flow ofhydraulic fluid through the first hydraulic fluid channel (531). Thefluid circuit (530) may be configured such that hydraulic fluid flowsinto the first hydraulic fluid channel (531) in the same direction forboth extension and compression of the piston (510). Therefore, the firstvalve (540) may comprise a unidirectional control valve rather than abi-directional valve. The first valve (540) may be a control valve suchas a proportional directional control valve. In some variations, thefirst valve (540) may comprise one or more of a voice coil valve,solenoid valve, and DC motor. The first valve (540) may have a rotary orlinear geometry. In some variations, resistance of the first valve (540)may be determined based upon input from one or more of the sensors(e.g., mechanical sensor) as described in more detail herein. In somevariations, the second through fifth valves (542, 544, 546, 548) may becheck valves configured to permit hydraulic fluid flow in a singledirection.

In some variations, an actuator (538) may be coupled to the first valve(540). The actuator (538) may be configured to bi-directionally drivethe first valve (540) to reciprocally and selectively position the firstvalve (540) to control fluid flow based on the polarity of the currentapplied to the actuator (538). Thus, the first valve (540) may bebi-directionally driven by the actuator (538).

The first valve (540) may include a sleeve having an orifice and a spoolmovable within the sleeve. The actuator (538) may be coupled to thefirst valve (540) to move the spool with respect to the orifice of thesleeve to vary a resistance to fluid flow through the valve (540). Insome variations, the actuator (538) may move a spool with respect to theorifice. Thus, the first valve (540) may be configured to set theresistance of fluid through the fluid circuit (530). As described inmore detail herein, the check valves may be configured such that fluidis permitted or resistant to flow through different fluid channels inresponse to compression and extension of the piston (510).

The fluid circuit (530) may be connected to a fluid sump (550). In somevariations, the fluid sump (550) may comprise a second piston (552) anda spring (554). The fluid sump (550) may comprise a cavity that servesas a reservoir for hydraulic fluid displaced by movement of the piston(510) in the cylinder (520). The spring (554) may be configured togenerate a spring force that acts on the second piston (552) as thevolume of the cavity increases with increased fluid volume, therebycreating an internal pressure that acts equally on both sides of thesecond piston (552). Since the pressure area is not equal on both sidesof the second piston (552), the net force acting on the second piston(552) is non-zero and may tend to push the piston shaft (51.2) out ofthe cylinder (520) resulting in a linear cylinder spring rate. Thecylinder spring rate may correspond to swing extension assistance thatmay assist extension of the knee.

The actuator (538) and first valve (540) may be coupled to a controller,such as controller (420) described herein. The controller may beconfigured to control actuator (538) and first valve (540), to therebycontrol a resistance of fluid flow through the hydraulic assembly (500),and thus the resistance to rotation of the prosthesis. For example,resistance of the first valve (540) may be determined based upon inputfrom one or more of the sensors as described in more detail herein.Accordingly, compression and extension of the hydraulic assembly (500)may be modified during the gait cycle of a prosthetic knee, and thuscontrol of the compression (flexion) and extension of a prosthetic jointduring gait.

FIG. 5B illustrates hydraulic fluid flow through the hydraulic assembly(500) in response to compression (560) of the piston (510) such as inresponse to a first state of a prosthetic knee (e.g., flexion state).For example, as the piston (510) reduces a volume of the second chamber(524) of the cylinder (520), hydraulic fluid may be permitted to enterthe fluid circuit (530) through the second cylinder port (528) and exitout of the first cylinder port (526). As illustrated in FIG. 513, thefluid circuit (530) may be configured to permit hydraulic fluid flowalong a first fluid path (570) sequentially through the second cylinderport (528), the fifth channel valve (548), the first valve (540) (e.g.,variable-resistance valve), the third channel valve (544), and into thefirst cylinder port (526). In some variations, the flexion state may beconfigured to permit fluid flow along a second fluid path (571) from thefirst valve (540) into the sump port (556). In this manner, fluid mayflow into and be held in the fluid sump (550) so as to displace thesecond piston (552). In some of these variations, the flexion state maybe configured to permit fluid flow simultaneously in the first andsecond fluid paths (570, 571).

In some variations, the flexion state may be configured to resist fluidflow through the second channel valve (542) and the fourth channel valve(546). For example, the second and fourth channel valves (542, 546) maybe check valves configured to resist flow received from a channel outlet(589) of the fifth check valve (548) and the second cylinder port (528),respectively. Conversely, the fifth check valve, first control valve,and third check valves (548, 540, 544) may be configured to allow fluidflow from the second cylinder port (528), a channel outlet (589) of thefifth check valve (548), and a channel outlet (581) of the first valve(540), respectively. Thus, hydraulic fluid flow may be configured toflow from the second chamber (524) through the hydraulic circuit (530)and fluid sump (550) and into the first chamber (522).

FIG. 5C illustrates hydraulic fluid flow through the hydraulic assembly(500) in response to extension of the piston (510) such as in responseto a second state of a prosthetic knee (e.g., extension state). Forexample, as the piston (510) reduces a volume of the first chamber (522)of the cylinder (520), hydraulic fluid may enter the fluid circuit (530)through the first cylinder port (526) and exit out of the secondcylinder port (528). As illustrated in FIG. 5C, the fluid circuit (530)may be configured to permit hydraulic fluid flow along a third fluidpath (572) sequentially through the first cylinder port (526), thesecond channel valve (542), the first valve (540) (e.g.,variable-resistance valve), the fourth channel valve (546), and into thesecond cylinder port (528). In some variations, the extension state maybe configured to permit fluid flow along a fourth fluid path (573)sequentially from the sump port (556) to the fourth channel valve (546).In this manner, fluid may flow out of the fluid sump (550) so as todisplace the second piston (552). In some of these variations, theextension state may be configured to permit fluid flow simultaneously inthe third and fourth fluid paths (572, 573).

In some variations, the extension state may be configured to resistfluid flow through the third channel valve (544) and the fifth channelvalve (548). The third and fifth channel valves (544, 548) may be checkvalves configured to resist flow received from the first cylinder port(526) and a channel outlet (583) of the second check valve (542),respectively. Conversely, the second check valve, first control valve,and fourth check valves (542, 540, 546) may be configured to allow fluidflow from the first cylinder port (526), a channel outlet (583) of thesecond check valve (542), and an outlet of the first valve (540),respectively. Thus, hydraulic fluid flow may be configured to flow fromthe first chamber (522) through the hydraulic circuit (530) and fluidsump (550) and into the second chamber (524).

C. Control Valve

The hydraulic systems described herein may include a control valveconfigured to set a rate of fluid flow through a fluid circuit orhydraulic assembly by variably setting an area of an opening throughwhich fluid flows. In some variations, a valve may comprise a sleevehaving one or more orifices through which fluid may flow and a spoolthat slidably moves within the sleeve to further set the area of fluidflow through the orifice. The control valves described herein may beprovided for use with a hydraulic assembly, limb prosthesis, orthotic,assistive device, or robotic linkage. FIG. 6A is a cross-sectional sideview of a valve (600) comprising a sleeve (610) and a spool (620). Thevalves disclosed herein may be driven by a valve actuator. The spool(620) may be slidable within a first lumen (612) of the sleeve (610) andmay be driven by an actuator (not shown) such as a voice coil actuator,solenoid actuator, or other actuator (e.g., DC brushless motor). Thesleeve (610) may have an inner diameter D. The spool (620) may define asecond lumen (622). The sidewalls of the sleeve (610) may define anorifice (614) having length L. As the spool (620) slides through thesleeve (610), portions of the spool (620) may overlap portions of theorifice (614) such that an open length of the orifice (614) may bedefined as L_(o). FIG. 6B is a side view of the sleeve (610)illustrating the orifice (614) depicted in FIG. 6A as having a width W.The orifice (614) may have an oblong shape (e.g., obround) as shown inFIG. 6B. However, the shape of the orifice (614) is not particularlylimited. In some variations, the orifice (614) may have a length L andL_(o) between about 0.5 mm and about 10.0 mm, an inner diameter Dbetween about 2 mm and about 10 mm, and a width W of between about 0.025mm and about 0.5 mm. For example, the length L and L_(o) may be betweenabout 2 mm and about 5 mm, the inner diameter D may be between about 2mm and about 5 mm, and the width W may be between about 0.05 mm andabout 0.2 mm.

As shown in FIG. 6F, a plurality of orifices (614, 616) (e.g., slits,holes) of varying shapes and sizes may be disposed radially about acircumference of the sleeve (610). In some variations, the number oforifices may be between 1 and 12. For example, the sleeve (610) maycomprise 4 orifices. A second orifice (616) may comprise a diameter Dhof between about 0.5 mm and about 6 mm. For example, the diameter Dh maybe between about 1.0 mm and about 3 mm. In some variations, the area ofan orifice may be between about 5 mm² and about 20 mm². For example, thearea of an orifice may be between about 10 mm² and about 15 mm².

The valve (600) depicted in FIG. 6A may be configured to linearly slidethe spool (620) within the sleeve (610). The orifice area of the valve(600) may be a function of a linear position of the spool (620) ascontrolled by a valve actuator. In other variations, the spool (620) maymove within the sleeve (610) in a rotary manner. In these variations,the orifice area of the valve (600) may be a function of an angularrotation of spool (620) relative to the orifice (614) as controlled by avalve actuator. Different actuation mechanisms exhibit varyingperformance characteristics including response rate, power consumption,size, cost, complexity, and the like. In some variations, a voice coilactuator may be coupled either directly or through one or more flexibleelements to a linear spool valve. Power to a voice coil actuator may berequired to maintain a specific valve position. In some variations usinga voice coil actuator, the valve may comprise a spring to set a powerOFF valve position when the actuator is in a power OFF state.

In some variations, the voice coil actuator may include a permanentmagnet and a coil movable with respect to each other. The permanentmagnet may generate a magnetic field in which the coil moves when acurrent is applied to the coil. In other variations, the coil may remainstationary as the magnet moves when a current is applied. The amount ofcurrent applied may correspond to a position of the coil with respect tothe magnet. The polarity of the current may correspond to a direction oftravel of the coil with respect to the magnet. For a voice coilactuator, the force produced may be proportional and substantiallylinear to the current applied such that the velocity of the coil may beproportional to the voltage applied. Thus, the voice coil actuator mayhave a substantially linear time and force response. A direction ofmovement of the coil may correspond to a polarity of the current. Insome variations, a voice coil actuator, and thus the voice coil controlvalve, may have a rapid response rate (i.e. greater than 100 cycles persecond), and a low power consumption (i.e. less than 1.8 Watts, or 150mAmps at 12V). Such an actuator and/or valve may be referred to hereinas a voice coil or voice coil valve.

In some variations, a solenoid valve may comprise a stationary iron corewith a coil and a movable iron armature. The armature may be configuredto move when current is applied to the coil. A solenoid actuator mayfurther comprise a spring configured for return movement when current isremoved from the coil. A solenoid actuator may operate unidirectionallyand against a return spring. Due to the spring return, the response timeof the valve in the return direction may be proportional to the springrate. Therefore, a stiff spring may be provided to achieve fast responsetimes. An armature force must overcome this spring force to stay at anygiven valve position. Therefore, the amount of power required to hold avalve position may increase proportionally to decreasing response timesof the valve. Solenoid valves may therefore provide ON/OFF operation andmay be non-linear (e.g., generate force proportional to the square ofthe current).

In some variations, a valve actuator may comprise a brushless DC motor.The motor may be coupled to a linear valve using a screw or a rotaryvalve either directly or indirectly through a transmission system. Thehydraulic assemblies disclosed herein may use any suitable valveactuator. Fluid flow through a valve (600) will be described withrespect to the cross-sectional side views depicted in FIGS. 6C-6E. InFIG. 6C, the spool (620) is at a first spool position (650) within thesleeve (610). At the first spool position (650), fluid flows at a firstvolumetric flow rate Qi from an area having a higher first pressure P₁through a first lumen (612) to an area having a lower second pressureP₂. The spool (620) overlaps only a small portion of the orifice (614)such that there is a relatively low level of resistance to fluid flowsuch that an amputee may experience a corresponding low level ofresistance to joint rotation.

In FIG. 6D, the spool (620) is at a second spool position (650) withinthe sleeve (610). At the second spool position (652), fluid flows at asecond volumetric flow rate Q₂ from an area having a higher firstpressure P₁ through a first lumen (612) to an area having a lower secondpressure P₂. The second volumetric flow rate Q₂ is less than the firstvolumetric flow rate Q₁. The spool (620) overlaps a significant portionof the orifice (614) such that there is a relatively intermediate and/orhigh level of resistance to fluid flow such that an amputee mayexperience a corresponding intermediate and/or high level of resistanceto joint rotation. In some variations, the first flow rate Q₁ may be upto about 40 ml/s and the second flow rate Q₂ may be up to about 40 ml/s.

In FIG. 6E, the spool (620) is at a third spool position (654) withinthe sleeve (610). At the third spool position (654), fluid does not flowthrough the valve (600). The orifice (614) is completely blocked by thespool (620). This condition may be referred to as lockout andcorresponds to maximum resistance to fluid flow where the prostheticjoint may be fixed at a particular angle. In some variations, the firstpressure P₁ may be up to about 4000 psi and the second pressure P₂ maybe up to about 4000 psi.

D. Power OFF Resistance

For safety reasons, when a prosthesis such as a prosthetic knee is in apower OFF state, the prosthetic knee may be configured to have highresistance (e.g., stiff) in flexion while allowing for free or lowresistance extension. In some variations, the power OFF flexionresistance may be configurable to accommodate different user preferencesand weights. As described in more detail herein, power OFF resistance ofa prosthetic knee may be implemented using a power OFF spool valve(e.g., ON/OFF spool valve) or a three-port valve (e.g., a proportionalvalve having an additional port).

1. Spool Valve

In some variations, the hydraulic circuit as described may comprise aprimary control valve (e.g., voice coil valve) and a secondary ON/OFFspool valve including a bias spring and a user adjustable variable flowresistor. When the hydraulic assembly is powered (e.g., when a valveactuator is powered), a secondary power OFF valve may be configured toclose and restrict flow through any of the secondary valve ports suchthat fluid flow bypasses the secondary power OFF valve. The primarycontrol valve may be configured to be spring-biased to fully close theorifice under a power OFF state while the secondary valve may beconfigured to be spring-biased to filly open each of the secondaryvalve's ports, thereby allowing fluid flow through each of the ports. Ina power OFF flexion state where the piston is compressed into thecylinder, fluid may be configured to flow through the user adjustablevariable flow resistor. In a power OFF extension stale where the pistonis extended from the cylinder, the variable flow resistor may bebypassed and the secondary valve may be configured to be fully open andallow unrestricted fluid flow. The spool valves described herein may beprovided for use with a hydraulic assembly, limb prosthesis, orthotic,assistive device, or robotic linkage.

FIG. 7A illustrates a hydraulic assembly (700) including a first piston(710) and hydraulic cylinder (720). The piston (710) may be slidablewithin the hydraulic cylinder (720). A piston shaft (712) coupled to thepiston (710) may compress or extend the piston (710) into the cylinder(720). The piston (710) may structurally separate the cylinder (720)into a first chamber (722) and an opposing second chamber (724). Thefirst chamber (722) may include a first cylinder port (726) and thesecond chamber (724) may include a second cylinder port (728). In somevariations, the first and second cylinder ports (726, 728) may belocated on a sidewall of the cylinder (720) on opposite sides of thepiston (710). In some variations, the first cylinder port (726) may belocated at a first end of the cylinder (720) while the second cylinderport (728) may be located at a second end of the cylinder (720) oppositethe first end.

The fluid circuit (730) may be coupled to the hydraulic cylinder (720)through the first and second cylinder ports (726, 728) such that thefluid circuit (730) may be configured to control a resistance ofhydraulic fluid through the hydraulic assembly (700). The fluid circuit(730) may include a plurality of hydraulic fluid channels configured tocontrol hydraulic fluid flow between the first chamber (722), the secondchamber (724), and a fluid sump (755). A first hydraulic fluid channel(731) may comprise a first channel inlet (780) (labeled in FIG. 7B), afirst channel outlet (781), and a first channel valve (741) configuredto set a variable resistance to flow through the first fluid channel(731). In some variations, the first channel valve (741) may be aunidirectional variable-resistance valve. A second fluid channel (732)may comprise a second channel inlet (782) (labeled in FIG. 7C), a secondchannel outlet (783), and a second channel valve (742). A third fluidchannel (733) may comprise a third channel inlet (784) (labeled in FIG.7B), a third channel outlet (785), and a third channel valve (743). Afourth fluid channel (734) may comprise a fourth channel inlet (786)(labeled in FIG. 7C), a fourth channel outlet (787), and a fourthchannel valve (744). A fifth fluid channel (735) may comprise a fifthchannel inlet (788) (labeled in FIG. 7B), a fifth channel outlet (789),and a fifth channel valve (745). A sixth fluid channel (736) maycomprise a sixth channel inlet (752), a sixth channel outlet (753), anda first user-adjustable variable flow resistor (748).

In some variations, a first interconnection (790) (e.g., intersection)may comprise the first channel inlet (780), second channel outlet (783),and the fifth channel outlet (789). A second interconnection (791) maycomprise the first cylinder port (726), the second channel inlet (782),and the third channel outlet (785). A third interconnection may comprisethe sump port (756), the third channel inlet (784), and the fourthchannel inlet (786). A fourth interconnection may comprise the secondcylinder port (728), the fourth channel outlet (787), and the fifthchannel inlet (788).

In some variations, the first channel inlet (780) may be connectedbetween the second channel valve (742) and the fifth channel valve(745). The first cylinder port (726) may be connected between the secondchannel valve (742) and the third channel valve (743). A sump port (756)may be connected between the third channel valve (743) and the fourthchannel valve (744). The second cylinder port (728) may be connectedbetween the fourth channel valve (744) and the fifth channel valve(745). The second channel valve (743) and fifth channel valve (745) maybe connected in series. The third channel valve (743) and fourth channelvalve (744) may be connected in series. The second channel valve (742)and the third channel valve (743) may be connected in parallel. Thefourth channel valve (744) and the fifth channel valve (745) may beconnected in parallel. A. first channel inlet (780) of the firsthydraulic fluid channel (731) may be connected between the second andfifth fluid channels (732, 735). A first channel outlet (781) of thefirst hydraulic fluid channel (731) may be connected between the thirdand fourth fluid channels (733, 734).

In some variations, the first variable flow resistor (748) may belocated between the third valve port (751) and the fourthinterconnection (793) along a sixth fluid channel (736). The sixth fluidchannel (736) may comprise a sixth channel inlet (752) at the fourthinterconnection (793) and a sixth channel outlet (753) connected to thethird valve port (751). In some variations, the first variable flowresistor (748) may comprise a unidirectional variable resistorconfigured to permit flow from the fourth interconnection (793) to thethird valve port (751). The first variable flow resistor (748) may beconfigured to block fluid flow from the third valve port (751) to thefourth interconnection (793) regardless of whether the sixth valve (746)is open or closed.

The first valve (741) may be configured to set a resistance to flow ofhydraulic fluid through the first hydraulic fluid channel (731). Thefluid circuit (730) may be configured such that hydraulic fluid flowsinto the first hydraulic fluid channel (731) in the same direction forboth extension and compression of the piston (710). Therefore, the firstvalve (741) may comprise a unidirectional control valve. The first valve(741) may be a control valve such as a proportional directional controlvalve. In some variations, the first valve (741) may comprise one ormore of a voice coil valve, solenoid valve, and DC motor. The firstvalve (741) may have a rotary or linear geometry. In some variations,the second through fifth valves (742, 743, 744, 745) may be check valvesconfigured to permit hydraulic fluid flow in a single direction.

In some variations, an actuator (754) may be coupled to the first valve(741). The actuator (754) may be configured to bi-directionally drivethe first valve (741) to reciprocally and selectively position the firstvalve (741) based on the polarity of the current applied to the actuator(754). Thus, the first valve (741) may be bi-directionally driven by theactuator (754).

The first valve (74 I) may include a sleeve having an orifice and aspool movable within the sleeve. The actuator (754) may be coupled tothe first valve (741) to move spool with respect to the orifice of thesleeve to vary a resistance to fluid flow through the first valve (741).In some variations, the actuator (754) may move a spool with respect tothe orifice. Thus, the first valve (741) may be configured to set theresistance of fluid through the fluid circuit (730). As described inmore detail herein, the check valves may be configured such that fluidflows through different fluid channels under compression and extensionof the piston (710).

The fluid circuit (730) may be connected to a fluid sump (755). In somevariations, the fluid sump (755) may comprise a second piston (758) anda second spring (759). The fluid sump (755) may comprise a cavity thatserves as a reservoir for hydraulic fluid displaced by movement of thepiston (710) in the cylinder (720). The fluid sump (755) may comprise afirst sump port (756) and a second sump port (757). The second spring(759) may be configured to generate a spring force that acts on thesecond piston (758) as the volume of the cavity increases with increasedfluid volume, thereby creating an internal pressure that acts equally onboth sides of the second piston (758). Since the pressure area is notequal on both sides of the second piston (758), the net force acting onthe second piston (758) is non-zero and may tend to push the pistonshaft (712) out of the cylinder (720) resulting in a linear cylinderspring rate. The cylinder spring rate may correspond to swing extensionassistance that may assist extension of the knee.

In some variations, the hydraulic circuit (730) may comprise a sixthvalve (746) (e.g., power OFF spool valve) that may be a three-way orthree-port valve that is normally open. In some variations, the sixthvalve (746) may comprise a first spring (747), a first valve port (749),a second valve port (750), and a third valve port (751). The sixth valve(746) may be configured to permit fluid passage between the first,second, and third valve ports (749, 750, 751) when open, and block fluidpassage between the first, second, and third valve ports (749, 750, 751)when closed. The first valve port (749) may be connected to the fluidsump (755) at the second sump port (757). The second valve port (750)may be connected to the second interconnection (791), and the thirdvalve port (751) may be connected to the fourth interconnection (793).

The actuator (754) and first valve (741) may be coupled to a controller,such as controller (420) described herein. The controller may beconfigured to control actuator (754) and first valve (741), to therebycontrol a resistance of fluid flow through the hydraulic assembly (700),and thus the resistance to rotation of the prosthesis. Accordingly,compression and extension of the hydraulic assembly (700) may bemodified during the gait cycle of a prosthetic knee, and thus control ofthe compression and extension of a prosthetic joint during gait.

FIG. 7B illustrates hydraulic fluid flow through the hydraulic assembly(700) in response to compression (760) of the piston (710) such as inresponse to a power ON flexion state of a prosthetic knee. For example,as the piston (710) reduces a volume of the second chamber (724) of thecylinder (720), hydraulic fluid may enter the fluid circuit (730)through the second cylinder port (728) and exit out of the firstcylinder port (726). As illustrated in FIG. 7B, the fluid circuit (730)may be configured to permit hydraulic fluid flow along a first path(770) sequentially through the second cylinder port (728), the fifthchannel valve (745), the first valve (741) (e.g., variable-resistancevalve), the third channel valve (743), and into the first cylinder port(726). In some variations, the flexion state may be configured to permitfluid flow along a second path (771) sequentially through the secondcylinder port (728), the fifth channel valve (745), the first valve(741), and into the sump port (756). In some of these variations, theflexion state may be configured to permit fluid flow simultaneously inthe first and second paths (770, 771).

In some variations, the flexion state may be configured to resist fluidflow through the second channel valve (742) and the fourth channel valve(744). The second and fourth channel valves (742, 744) may be checkvalves configured to resist flow received from an outlet of the fifthcheck valve (745) and the second cylinder port (728), respectively.Conversely, the fifth check valve, first control valve, and third checkvalves (745, 741, 743) may be configured to permit fluid flow from thesecond cylinder port (728), a channel outlet (789) of the fifth checkvalve (745), and a channel outlet (781) of the first valve (741),respectively. Thus, hydraulic fluid flow may be configured to permitflow from the second chamber (724) through the hydraulic circuit (730)and fluid sump (755) and into the first chamber (722).

FIG. 7C illustrates hydraulic fluid flow through the hydraulic assembly(700) in response to extension of the piston (710) such as due to powerON extension of a prosthetic knee. For example, as the piston (710)reduces a volume of the first chamber (726) of the cylinder (720),hydraulic fluid may enter the fluid circuit (730) through the firstcylinder port (726) and exit out of the second cylinder port (728). Asillustrated in FIG. 7C, the fluid circuit (730) may be configured topermit hydraulic fluid flow along a third fluid path (772) sequentiallythrough the first cylinder port (726), the second channel valve (742),the first valve (741) (e.g., variable-resistance valve), the fourthchannel valve (744), and into the second cylinder port (728). In somevariations, the extension state may be configured to permit fluid flowalong a fourth fluid path (773) sequentially from the sump port (756) tothe fourth channel valve (744). In some of these variations, theextension state may be configured to permit fluid flow simultaneously inthe third and fourth paths (772, 773).

In some variations, the extension state may be configured to resistfluid flow through the third channel valve (743) and the fifth channelvalve (745). For example, the third and fifth channel valves (743, 745)may be check valves configured to resist flow received from the firstcylinder port (726) and a channel outlet (783) of the second check valve(742), respectively. Conversely, the second check valve, first controlvalve, and fourth check valves (742, 740, 744) may be configured topermit fluid flow from the first cylinder port (726), a channel outlet(783) of the second check valve (742), and a channel outlet (781) of thefirst valve (741), respectively. Thus, hydraulic fluid flow may beconfigured to permit flow from the first chamber (722) through thehydraulic circuit (730) and fluid sump (755) and into the second chamber(724).

FIG. 7D illustrates hydraulic fluid flow through the hydraulic assembly(700) in response to a power OFF flexion state of a prosthetic knee. Forexample, as the piston (710) reduces a volume of the second chamber(724) of the cylinder (720), hydraulic fluid may enter the fluid circuit(730) through the second cylinder port (728) and exit out of the firstcylinder port (726). As illustrated in FIG. 7D, the fluid circuit (730)may be configured to permit hydraulic fluid flow along a fifth fluidpath (774) sequentially through the second cylinder port (728), thefirst variable flow resistor (748), the third valve port (751), thesecond valve port (750), and into the first cylinder port (726). Thehydraulic circuit (730) may be further configured to permit fluid flowalong a sixth fluid path (775) from the first valve port (749) to thefluid sump (755).

FIG. 7E illustrates hydraulic fluid flow through the hydraulic assembly(700) in response to extension of the piston (710) such as due to powerOFF extension state of a prosthetic knee. For example, as the piston(710) reduces a volume of the first chamber (722) of the cylinder (720),hydraulic fluid may enter the fluid circuit (730) through the firstcylinder port (726) and exit out of the second cylinder port (728). Asillustrated in FIG. 7E, the fluid circuit (730) may be configured topermit hydraulic fluid flow along a seventh fluid path (776)sequentially through the first cylinder port (526), the second valveport (750), the first valve port (749), the second sump port (757), thefirst sump port (756), the fourth fluid channel (734), and into thesecond cylinder port (528).

FIGS. 8A-8D are cross-sectional side views of an exemplary variation ofa control valve. FIG. 8A illustrates a cross-sectional side view of anormally open proportional spool valve (800), FIG. 8B illustrates across-sectional side view of a power OFF valve (802), and FIG. 8Cillustrates a schematic diagram of the valve (800). A control valve(800) may comprise a housing (810) having a first end (812), a secondend (814), and one or more lateral openings (816). The control valve(800) may comprise a hydraulic valve (820) comprising a sleeve (830), aspool (840) defining one or more apertures (842), and a bias spring(860). The control valve (800) may further comprise an actuator (850)configured to drive the hydraulic valve (820). The actuator (850) maycomprise a magnet (852), a coil bobbin (854), and a coil (846). In somevariations, the magnet (852) may comprise an inner diameter of betweenabout 2 mm and about 60, an outer diameter of between about 2.5 mm andabout 70 mm, and a length of between about 1.5 mm and about 50 mm. Forexample, the magnet may comprise an inner diameter of between about 15mm and about 25 mm, an outer diameter of between about 20 mm and about30 mm, and a length of between about 15 mm and about 20 mm. In somevariations, the magnet (852) may comprise neodymium although anysuitable magnetic composition may be used. FIG. 8C further illustrates afirst valve port (870), a second valve port (872), and a third valveport (874). FIG. 8D illustrates a schematic diagram of the valve forpower OFF flexion. The spool (840) may be positioned with respect to thesleeve (830) such that fluid flow is blocked for each of the first,second, and third valve ports (870, 872, 874). FIG. 8E illustrates aschematic diagram of the valve for power OFF extension. The spool (840)may be aligned with an orifice (832) of the sleeve (830) such that fluidmay flow from a first valve port (870) into the second and third valveports (872, 874). The first, second, and third valve ports (870, 872,874) may each comprise an area of between about 0.5 mm² and about 30mm², and be separated from an adjacent port by between about 0.25 mm andabout 30 mm. In some variations, the number of lateral openings (816)may be between about 1 and about 15. For example, the control valve(800) may comprise about 4 lateral openings (816). In some variations,the lateral opening (816) may have a diameter of between about 1 mm andabout 6 mm. For example, the diameter of the lateral opening (816) maybe between about 2 mm and about 4 mm.

2. Three-Port Valve

The three-port design adds an additional port to the main proportionalspool valve. When the power is on, the spool may act to continually varythe orifice area depending on the desired resistance. Accordingly, aresistance to fluid flow may be controlled using the spool valve and maybe varied between a fully locked position and a fully open position byvarying the orifice area. When the power is off, the spool may springbiased such that a third port in the valve is opened, thereby permittingflow to a different section of the hydraulic circuit. In somevariations, the three-port valve may be voice-coil actuated and servocontrolled with a magnetic sensor for position feedback. The three-portvalves described herein may be provided for use with a hydraulicassembly, limb prosthesis, orthotic, assistive device, or roboticlinkage.

In some variations, a hydraulic assembly or system may comprise asingle-ended cylinder coupled to a fluid circuit having a unidirectionalthree-port valve. This unidirectional control valve may set resistanceto hydraulic fluid flow in both flexion (e.g., cylinder compressing) andextension (e.g., cylinder extending). The control valve may beunidirectional in that the fluid circuit ensures fluid flow in a singledirection into the control valve for both compression and extension. Ina power OFF state, the valve may move to the power OFF position wherefluid may flow through a user-adjustable variable flow resistor tocontrol power OFF flexion resistance. For example, extension resistancein a power OFF position may correspond to an open area of the fluid flowpassages in the valve, as described in more detail herein.

FIG. 9A illustrates a hydraulic assembly (900) including a first piston(910), hydraulic cylinder (920), and a hydraulic fluid flow circuit(930). The piston (910) may be slidable within a hydraulic cylinder(920). A piston shaft (912) coupled to the piston (910) may compress orextend the piston (910) into the cylinder (920). The piston (910) maystructurally separate the cylinder (920) into a first chamber (922) andan opposing second chamber (924). The first chamber (922) may include afirst cylinder port (926) and the second chamber (924) may include asecond cylinder port (928). In some variations, the first and secondcylinder ports (926, 928) may be located on a sidewall of the cylinder(920) on opposite sides of the piston (910). In some variations, thefirst cylinder port (926) may be located at a first end of the cylinder(920) while the second cylinder port (928) may be located at a secondend of the cylinder (920) opposite the first end.

The fluid circuit (930) may be coupled to the hydraulic cylinder (920)through the first and second cylinder ports (926, 928) such that thefluid circuit (930) may be configured to control a resistance ofhydraulic fluid through the hydraulic assembly (900). The fluid circuit(930) may include a plurality of hydraulic fluid channels configured tocontrol hydraulic fluid flow between the first chamber (922), the secondchamber (924), and a fluid sump (950). A first hydraulic fluid channel(931) may comprise a first channel inlet (980) (labeled in FIG. 9B), afirst channel outlet (981), and a first channel valve (940) configuredto set a variable resistance to flow through the first fluid channel(931). In some variations, the first channel valve (940) may comprise athree-way spool valve and a secondary channel inlet (941). In somevariations, the first channel valve (940) may comprise a spring and maybe configured to normally permit fluid communication between thesecondary channel inlet (941) and the first channel outlet (981) whenthe first channel valve (940) is an unpowered three-way spool valve. Asecond fluid channel (932) may comprise a second channel inlet (982)(labeled in FIG. 9C), a second channel outlet (983), and a secondchannel valve (942). A third fluid channel (933) may comprise a thirdchannel inlet (984) (labeled in FIG. 9B), a third channel outlet (985),and a third channel valve A fourth fluid channel (934) may comprise afourth channel inlet (986) (labeled in FIG. 9E), a fourth channel outlet(987), and a fourth channel valve (944). A fifth fluid channel (935) maycomprise a fifth channel inlet (988) (labeled in FIG. 9B), a fifthchannel outlet (989), and a fifth channel valve (945). A seventh fluidchannel (937) may comprise a seventh channel inlet (961) (labeled inFIG. 9E), a seventh channel outlet (962), and a seventh channel valve(947). The seventh channel inlet (961) may be connected to the firstcylinder port (926) or a second interconnection (991) (e.g.,intersection). In some variations, the seventh channel valve (947) maycomprise a check valve. An eighth fluid channel (938) may comprise aneighth channel inlet (963) (labeled in FIG. 9E), and eighth channeloutlet (964), and a second variable flow resistor (948).

In some variations, a first interconnection (990) (e.g., intersection)may comprise the first channel inlet (980), second channel outlet (983),and the fifth channel outlet (989). In some variations, the firstinterconnection (990) may further comprise the eighth channel inlet(963) (labeled in FIG. 9E). A second interconnection (991) may comprisethe first cylinder port (926), the second channel inlet (982), and thethird channel outlet (985). A third interconnection (992) may comprisethe sump port (956), the third channel inlet (984), and the fourthchannel inlet (986). A fourth interconnection (993) may comprise thesecond cylinder port (928), the fourth channel outlet (987), and thefifth channel inlet (988). A fifth interconnection (994) may comprisethe seventh fluid channel outlet (962), the eighth channel inlet (963),the eighth channel outlet (964), and the secondary channel inlet (941)of the first valve (940).

In some variations, the first channel inlet (980) may be connectedbetween the second channel valve (942) and the fifth channel valve(945). The first cylinder port (926) may be connected between the secondchannel valve (942) and the third channel valve (943). A. sump port(956) may be connected between the third channel valve (943) and thefourth channel valve The second cylinder port (928) may be connectedbetween the fourth channel valve (944) and the fifth channel valve(945). The second channel valve (942) and fifth channel valve (945) maybe connected in series. The third channel valve (943) and fourth channelvalve (943) may be connected in series. The second channel valve (942)and the third channel valve (943) may be connected in parallel. Thefourth channel valve (944) and the fifth channel valve (945) may beconnected in parallel. A first channel inlet (980) of the firsthydraulic fluid channel (931) may be connected between the second andfifth fluid channels (932, 935). A first channel outlet (981) of thefirst hydraulic fluid channel (931) may be connected between the thirdand fourth fluid channels (933, 934).

The first valve (940) may be configured to set a resistance to flow ofhydraulic fluid through the first hydraulic fluid channel (931). Thefluid circuit (930) may be configured such that hydraulic fluid flowsinto the first hydraulic fluid channel (931) in the same direction forboth extension and compression of the piston (910). Therefore, the firstvalve (940) may comprise a unidirectional control valve rather than abi-directional valve. The first valve (940) may be a control valve suchas a proportional directional control valve. In some variations, thefirst valve (940) may comprise one or more of a voice coil valve,solenoid valve, and DC motor. The first valve (940) may have a rotary orlinear geometry. In some variations, the second through fifth valves(942, 943, 944, 945) may be check valves configured to permit hydraulicfluid flow in a single direction.

In some variations, an actuator (939) may be coupled to the first valve(940). The actuator (939) may be configured to bi-directionally drivethe first valve (940) to reciprocally and selectively position the firstvalve (940) based on the polarity of the current applied to the actuator(939). Thus, the first valve (940) may be bi-directionally driven by theactuator (939).

The first valve (940) may include a sleeve having an orifice and a spoolmovable with respect to the sleeve. The actuator (939) may be coupled tothe first valve (940) to move the spool with respect to orifice to varya resistance to fluid flow through the first valve (940). In somevariations, the actuator (939) may move a spool with respect to theorifice. Thus, the first valve (940) may be configured to set theresistance of fluid through the fluid circuit (930). As described inmore detail herein, the check valves may be configured such that fluidflows through different fluid channels under compression and extensionof the piston (910).

The fluid circuit (930) may be connected to a fluid sump (950). In somevariations, the fluid sump (950) may comprise a spring-biased secondpiston (951) and a spring (952). The fluid sump (950) may comprise acavity that serves as a reservoir for hydraulic fluid displaced bymovement of the piston (910) in the cylinder (920). The spring (952) maybe configured to generate a spring force that acts on the second piston(951) as the volume of the cavity increases with increased fluid volume,thereby creating an internal pressure that acts equally on both sides ofthe second piston (951). Since the pressure area is not equal on bothsides of the second piston (951), the net force acting on the secondpiston (951) is non-zero and may tend to push the piston shaft (912) outof the cylinder (920) resulting in a linear cylinder spring rate. Thecylinder spring rate may correspond to swing extension assistance thatmay assist extension of the knee.

The actuator (939) and first valve (940) may be coupled to a controller,such as controller (420) described herein. The controller may beconfigured to control actuator (939) and first valve (940), to therebycontrol a resistance of fluid flow through the hydraulic assembly (900),and thus the resistance to rotation of the prosthesis. Accordingly,compression and extension of the hydraulic assembly (900) may bemodified during the gait cycle of a prosthetic knee, and thus control ofthe compression and extension of a prosthetic joint during gait.

FIG. 9B illustrates hydraulic fluid flow through the hydraulic assembly(900) in response to compression (968) of the piston (910) such as inresponse to a power ON flexion state of a prosthetic knee. For example,as the piston (910) reduces a volume of the second chamber (924) of thecylinder (920), hydraulic fluid may be permitted to enter the fluidcircuit (930) through the second cylinder port (928) and exit out of thefirst cylinder port (926). As illustrated in FIG. 9B, the fluid circuit(930) may be configured to permit hydraulic fluid flow along a firstfluid path (970) sequentially through the second cylinder port (928),the fifth channel valve (945), the eight fluid channel (980), the firstvalve (940) (e.g., variable-resistance three-port valve), the thirdchannel valve (943), and into the first cylinder port (926). In somevariations, the flexion state may be configured to permit fluid flowalong a second fluid path (971) from the first valve (940) into the sumpport (956). In some of these variations, the flexion state may beconfigured to permit fluid flow simultaneously in the first and secondfluid paths (970, 971).

In some variations, the flexion state may be configured to resist fluidflow through the second channel valve (942) and the fourth channel valve(944). The second and fourth channel valves (942, 944) may be checkvalves configured to resist flow received from an outlet of the fifthcheck valve (945) and the second cylinder port (928), respectively.Conversely, the fifth check valve, first control valve, and third checkvalves (945, 940, 943) may be configured to allow fluid flow from thesecond cylinder port (928), an outlet of the fifth check valve (948),eighth channel inlet (963), and a secondary channel inlet (941),respectively. Thus, hydraulic fluid flow may be configured to flow fromthe second chamber (924) through the hydraulic circuit (930) and fluidsump (950) and into the first chamber (922).

FIG. 9C illustrates hydraulic fluid flow through the hydraulic assembly(900) in response to extension (969) of the piston (910) such as due topower ON extension of a prosthetic knee. For example, as the piston(910) reduces a volume of the first chamber (926) of the cylinder (920),hydraulic fluid may enter the fluid circuit (930) through the firstcylinder port (922) and exit out of the second cylinder port (928). Asillustrated in FIG. 9C, the fluid circuit (930) may be configured topermit hydraulic fluid flow along a third fluid path (972) sequentiallythrough the first cylinder port (926), the second channel valve (942),the seventh fluid channel (937), the secondary channel inlet (941), thefirst valve (940) (e.g., three-way valve), the fourth channel valve(944), and into the second cylinder port (928). In some variations, theextension state may be configured to permit fluid flow along a fourthfluid path (973) sequentially from the sump port (956) to the fourthchannel valve (944). In some of these variations, the extension statemay be configured to permit fluid flow simultaneously in the third andfourth fluid paths (972, 973).

In some variations, the extension state may be configured to resistfluid flow through the third channel valve (943) and the fifth channelvalve (945). The third and fifth channel valves (943, 945) may be checkvalves configured to resist flow received from the first cylinder port(926) and a channel outlet (983) of the second check valve (942),respectively. Conversely, the second check valve, first control valve,and fourth check valves (942, 940, 944) may be configured to allow fluidflow from the first cylinder port (926), a channel outlet (983) of thesecond check valve (942), and a channel outlet (981) of the first valve(940), respectively. Thus, hydraulic fluid flow may be configured toflow from the first chamber (922) through the hydraulic circuit (930)and fluid sump (950) and into the second chamber (924).

FIG. 9D illustrates hydraulic fluid flow through the hydraulic assembly(900) in response to compression (968) of the piston (910) such as inresponse to a power OFF flexion state of a prosthetic knee. For example,as the piston (910) reduces a volume of the second chamber (924) of thecylinder (920), hydraulic fluid may be permitted to enter the fluidcircuit (930) through the second cylinder port (928) and exit out of thefirst cylinder port (926). As illustrated in FIG. 9D, the fluid circuit(930) may be configured to permit hydraulic fluid flow along an eighthfluid path (978) sequentially through the second cylinder port (928),the fifth fluid channel (935), the eighth fluid channel (938), thesecondary channel inlet (941) of the first valve (940), the third fluidchannel (933), and into the first cylinder port (926). In somevariations, the flexion state may be configured to permit fluid flowalong a second fluid path (971) from the first valve (940) into the sumpport (956). In some of these variations, the flexion state may beconfigured to permit fluid flow simultaneously in the first and secondfluid paths (970, 971). In some of these variations, fluid may flow fromthe first channel outlet (981) to the fluid sump (950).

FIG. 9E illustrates hydraulic fluid flow through the hydraulic assembly(900) in response to extension of the piston (910) such as due to powerOFF extension state of a prosthetic knee. For example, as the piston(910) reduces a volume of the first chamber (922) of the cylinder (920),hydraulic fluid may enter the fluid circuit (930) through the firstcylinder port (926) and exit out of the second cylinder port (928). Asillustrated in FIG. 9E, the fluid circuit (930) may be configured topermit hydraulic fluid flow along a ninth fluid path (979) sequentiallythrough the first cylinder port (926), the seventh fluid channel (937),the secondary channel inlet (941), the fourth fluid channel (934), intothe second cylinder port (928). In some of these variations, fluid flowmay be provided from the fluid sump (950) to the fourth fluid channel(934).

Fluid flow through a valve (1000) will be described with respect to thecross-sectional side views depicted in FIGS. 10A-10D. In FIG. 10A, thespool (1020) is at a first spool position (1050) within the sleeve(1010). At the first spool position (1050), fluid flows at a firstvolumetric flow rate Qi from an area having a higher first pressure PIthrough a first lumen (:1012) to an area having a lower second pressureP2 . The spool (1020) overlaps only a small portion of the first orifice(1014) such that there is a relatively low level of resistance to fluidflow such that an amputee may experience a low level of resistance tojoint rotation range. The second orifice (1016) is completely blocked bythe spool (1020).

In FIG. 10B, the spool (1020) is at a second spool position (1052)within the sleeve (1010). At the second spool position (1052), fluidflows at a second volumetric flow rate Q₂ from an area having a higherfirst pressure P₁ through a first lumen (1012) to an area having a lowersecond pressure P₂. The second volumetric flow rate Q₂ is less than thefirst volumetric flow rate Q₁. The spool (1020) overlaps a significantportion of the first orifice (1014) such that there is a relativelyintermediate and/or high level of resistance to fluid flow such that anamputee may experience an intermediate and/or high level of resistanceto joint rotation. The second orifice (1016) is completely blocked bythe spool (1020).

In FIG. 10C, the spool (1020) is at a third spool position (1054) withinthe sleeve (:1010). At the third spool position (1054), fluid does notflow through the valve (1000) (e.g., lockout). The first orifice (1014)and second orifice (1016) are completely blocked by the spool (1020). Inthis configuration, the valve (1000) provides maximum resistance tofluid flow such that the prosthetic joint may be fixed at a particularangle.

In FIG. 10D, the spool (1020) is at a fourth spool position (1056)within the sleeve (1010). At the fourth spool position (1056), the firstorifice (1014) is completely blocked by the spool (1020). However, thesecond orifice (1016) becomes unblocked such that fluid may flow from anarea having a higher third pressure P₃ through a second lumen (1022) toan area having a lower second pressure P₂. In some variations, the firstpressure P₁ may be up to about 4000 psi, the second pressure P₂ may beup to about 4000 psi, and the third pressure P₃ may be up to about 4000psi.

FIGS. 11A-11E are cross-sectional side views of an exemplary variationof a control valve. FIG. 11A illustrates a cross-sectional side view ofa normally closed proportional three-port spool valve (1100). FIGS. 11Band 11D illustrate schematic diagrams of the valve (1100). A controlvalve (1100) may comprise a housing (1110) having a first end (1112), asecond end (1114), and one or more lateral openings (1116). The controlvalve (1100) may comprise a hydraulic valve (1120) comprising a sleeve(1130) defining an orifice (1132), a spool (1140) defining one or moreapertures (1142), and a bias spring (1160). The control valve (1100) mayfurther comprise an actuator (1150) configured to drive the hydraulicvalve (1120). The actuator (1150) may comprise a magnet (1152) (e.g.,voice coil magnet), a coil bobbin (1154), and a coil (1146) (e.g., voicecoils). FIGS. 11B and 11D further illustrate a first valve port (1170),a second valve port (1172), and a third valve port (1174). FIG. 11Dillustrates a schematic diagram of the valve for power OFF flexion. Thespool (1140) may be positioned with respect to the sleeve (1130) suchthat fluid flow is blocked for the third valve port (1174) and permittedfor fluid to flow from the second valve port (1172) into the first valveport (1170). FIG. 11E illustrates a schematic diagram of the valve forpower OFF extension. The spool (1140) may be aligned with the orifice(1132) of the sleeve (1130) such that fluid may flow enter a third valveport (1174) into the first valve port (1170).

Knee torque calculations may be used to control systems and devicesdescribed herein. In some variations, torque estimation may be achievedby placing a load cell in line with the hydraulic cylinder. By knowingthe angle of the knee, the moment arm of the cylinder may be calculated.Combining the moment arm with the load on the cylinder allows forcalculation of the torque about the knee joint. The load cell may beplaced in the distal cylinder mount, the piston shaft, or the cylinder.In some variations, pressure gauges internal to the cylinder may be usedto measure the differential pressure and may also be used to calculatethe load on the cylinder.

FIG. 13A is a cross-sectional side view of another exemplary variationof a control valve (1300). A control valve (1300) may comprise a housing(1310) having a first end (1312), a second end (1314), and one or morelateral openings (1316). The control valve (1300) may comprise ahydraulic valve (1320) comprising a sleeve (1310), a spool (1320)defining one or more apertures (1342), and a spring (1360). The controlvalve (1300) may further comprise an actuator (1350) configured to drivethe hydraulic valve (1320). The actuator (1350) may comprise a magnet(1352) and a coil (1346). In some variations, the magnet (1352) maycomprise an inner diameter of between about 2 mm and about 60, an outerdiameter of between about 2.5 mm and about 70 mm, and a length ofbetween about 1.5 mm and about 50 mm. For example, the magnet (1352) maycomprise an inner diameter of between about 15 mm and about 25 mm, anouter diameter of between about 20 mm and about 30 mm, and a length ofbetween about 15 mm and about 20 mm. In some variations, the magnet(1352) may comprise neodymium although any suitable magnetic compositionmay be used.

FIGS. 13B-13E are illustrative schematic views of a variation of acontrol valve. FIG. 13B is a cross-sectional side view of a sleeve andspool, and FIGS. 13C-13E are side views of the sleeve, spool, andorifice in different resistance states. FIG. 13B is a cross-sectionalside view of a valve (1300) comprising a sleeve (1310) and a spool(1320). The spool (1320) may be slidable within a first lumen (1312) ofthe sleeve (1310) and may be driven by an actuator (not shown) such as avoice coil actuator, solenoid actuator, or other actuator (e.g., DCbrushless motor). The sidewalls of the sleeve (1310) may define one ormore orifices (1314). As the spool (1320) slides through the sleeve(1310), portions of the spool (1320) may overlap portions of the orifice(1314). FIG. 13C is a side view of the sleeve (1310) illustrating theorifice (1314) depicted in FIG. 13B as having a hole (1318 a) and a slit(1318 b). As shown in FIGS. 13C-13F, the orifice (1314) may have akeyhole-like shape. However, the shape of the orifice (1314) is notparticularly limited. FIG. 13D illustrates the valve (1300) in a highresistance state where the hole (1318 a) and a large portion of slit(1318 b) are blocked by the spool (1320), thereby limiting fluid flow.FIG. 13E illustrates the valve (1300) in an open state where the spool(1320) blocks little, if any, portion of the orifice (1314).

The valve (1300) depicted in FIGS. 13A-13E may be configured to linearlyslide the spool (1320) within the sleeve (1310). The orifice area of thevalve (1300) may be a function of a linear position of the spool (1320)as controlled by a valve actuator. In other variations, the spool (1320)may move within the sleeve (1310) in a rotary manner. In thesevariations, the orifice area of the valve (1300) may be a function of anangular rotation of spool (1320) relative to the orifice (1314) ascontrolled by a valve actuator. Different actuation mechanisms exhibitvarying performance characteristics including response rate, powerconsumption, size, cost, complexity, and the like. In some variations, avoice coil actuator may be coupled either directly or through one ormore flexible elements to a linear spool valve. Power to a voice coilactuator may be required to maintain a specific valve position. In somevariations using a voice coil actuator, the valve may comprise a springto set a power OFF valve position when the actuator is in a power OFFstate.

In some variations, the voice coil actuator may include a permanentmagnet and a coil movable with respect to each other. The permanentmagnet may generate a magnetic field in which the coil moves when acurrent is applied to the coil. In other variations, the coil may remainstationary as the magnet moves when a current is applied. The amount ofcurrent applied may correspond to a position of the coil with respect tothe magnet. The polarity of the current may correspond to a direction oftravel of the coil with respect to the magnet. For a voice coilactuator, the force produced may be proportional and substantiallylinear to the current applied such that the velocity of the coil may beproportional to the voltage applied. Thus, the voice coil actuator mayhave a substantially linear time and force response. A direction ofmovement of the coil may correspond to a polarity of the current. Insome variations, a voice coil actuator, and thus the voice coil controlvalve, may have a rapid response rate (i.e. greater than 100 cycles persecond), and a low power consumption (i.e. less than 1.8 Watts, or 150mAmps at 12V). Such an actuator and/or valve may be referred to hereinas a voice coil or voice coil valve.

In some variations, a solenoid valve may comprise a stationary iron corewith a coil and a movable iron armature. The armature may be configuredto move when current is applied to the coil. A solenoid actuator mayfurther comprise a spring configured for return movement when current isremoved from the coil. A solenoid actuator may operate unidirectionallyand against a return spring. Due to the spring return, the response timeof the valve in the return direction may be proportional to the springrate. Therefore, a stiff spring may be provided to achieve fast responsetimes. An armature force must overcome this spring force to stay at anygiven valve position. Therefore, the amount of power required to hold avalve position may increase proportionally to decreasing response timesof the valve. Solenoid valves may therefore provide ON/OFF operation andmay be non-linear (e.g., generate force proportional to the square ofthe current). In some variations, a valve actuator may comprise abrushless DC motor. The motor may be coupled to a linear valve using ascrew or a rotary valve either directly or indirectly through atransmission system. The hydraulic assemblies disclosed herein may useany suitable valve actuator.

FIGS. 13F-13I depict fluid flow through a valve (1300) and in particularillustrate schematic diagrams of the valve in a fully open state (FIG.13F), high resistance state (FIG. 13G), lock out state (FIG. 13H), andpower OFF state (FIG. 13T). For the sake of clarity, the same elementsin FIG. 13F are not labeled in FIGS. 13G-13I.

In FIG. 13F, the spool (1320) is at a first spool position within thesleeve (1310). At the first spool position, fluid flows from the secondport (1372) through the first port (1370) with flow blocked from thethird port (1374). In the first spool position, there is a relativelylow level of resistance to fluid flow such that an amputee mayexperience a corresponding low level of resistance to joint rotation.

In FIG. 13G, the spool (1320) is at a second spool position within thesleeve (1310). At the second spool position, fluid flow through thesecond port (1372) and the first port (1370) is relatively lower than inthe first spool position. For example, the spool (1320) overlaps asignificant portion of the orifice (1314) such that there is arelatively intermediate and/or high level of resistance to fluid flowsuch that an amputee may experience a corresponding intermediate and/orhigh level of resistance to joint rotation.

In FIG. 13H, the spool (1320) is at a third spool position within thesleeve (1310).

At the third spool position, fluid does not flow through the valve(1300). All of the orifices (1314) are completely blocked by the spool(1320). This condition may be referred to as lock out and corresponds tomaximum resistance to fluid flow where the prosthetic joint may be fixedat a particular angle.

As shown in FIG. 13I, when power is shut OFF, the spring (1360) may biasthe coil bobbin (1354) to a hard stop position and thereby permits fluidflow between the third port (1374) and first port (1370). The spool(1.320) in FIG. 131 is at a fourth spool position within the sleeve(1310). At the fourth spool position, fluid flows through the third port(1374) and the first port (1370) with fluid flow blocked with respect tothe second port (1372).

II. Methods

Also described here are methods for controlling rotational resistance ofa prosthesis using the systems and devices described herein. In somevariations, the process may begin by transmitting hydraulic fluid in thefluid circuit as described herein during the flexion state duringprosthesis flexion and when the prosthesis variable resistance valve ispowered. Hydraulic fluid may be transmitted in the fluid circuit asdescribed herein during the extension state during prosthesis extensionand when the prosthesis variable resistance valve is powered.

In some variations, the process may begin by transmitting hydraulicfluid in the fluid circuit as described herein during the flexion stateduring prosthesis flexion and when the prosthesis variable resistancevalve is powered. Hydraulic fluid may be transmitted in the fluidcircuit as described herein during the extension state during prosthesisextension and when the prosthesis variable resistance valve is powered.Hydraulic fluid may be transmitted in the fluid circuit as indicatedduring the power OFF flexion state during prosthesis flexion and whenthe prosthesis variable resistance valve is not powered

In some variations, the process may begin by transmitting hydraulicfluid in the fluid circuit as described herein during the flexion stateduring prosthesis flexion and when the prosthesis variable resistancevalve is powered. Hydraulic fluid may be transmitted in the fluidcircuit as described herein during the extension state during prosthesisextension and when the prosthesis variable resistance valve is powered.Hydraulic fluid may be transmitted in the fluid circuit as describedherein during the power OFF flexion state during prosthesis flexion andwhen the prosthesis variable resistance valve is not powered. Hydraulicfluid may be transmitted in the fluid circuit as described herein duringthe power OFF extension state during prosthesis extension and when theprosthesis variable resistance valve is not powered.

Some variations described herein relate to a computer storage productwith a non-transitory computer-readable medium (also may be referred toas a non-transitory processor-readable medium) having instructions orcomputer code thereon for performing various computer-implementedoperations. The computer-readable medium (or processor-readable medium)is non-transitory in the sense that it does not include transitorypropagating signals per se (e.g., a propagating electromagnetic wavecarrying information on a transmission medium such as space or a cable).The media and computer code (also may be referred to as code oralgorithm) may be those designed and constructed for the specificpurpose or purposes. Examples of non-transitory computer-readable mediainclude, but are not limited to, magnetic storage media such as harddisks, floppy disks, and magnetic tape; optical storage media such asCompact Disc/Digital Video Discs (CD/DVDs); Compact Disc-Read OnlyMemories (CD-ROMs), and holographic devices; magneto-optical storagemedia such as optical disks; solid state storage devices such as a solidstate drive (SSD) and a solid state hybrid drive (SSHD); carrier wavesignal processing modules; and hardware devices that are speciallyconfigured to store and execute program code, such asApplication-Specific Integrated Circuits (ASICs), Programmable LogicDevices (PLDs), Read-Only Memory (ROM), and Random-Access Memory (RAM)devices. Other variations described herein relate to a computer programproduct, which may include, for example, the instructions and/orcomputer code disclosed herein.

The systems, devices, and/or methods described herein may be performedby software (executed on hardware), hardware, or a combination thereof.Hardware modules may include, for example, a general-purpose processor(or microprocessor or microcon troller), a field programmable gate array(FPGA), and/or an application specific integrated circuit (ASIC).Software modules (executed on hardware) may be expressed in a variety ofsoftware languages (e.g., computer code), including C, C++, Java®,Python, Ruby, Visual Basic®, and/or other object-oriented, procedural,or other programming language and development tools. Examples ofcomputer code include, but are not limited to, micro-code ormicro-instructions, machine instructions, such as produced by acompiler, code used to produce a web service, and files containinghigher-level instructions that are executed by a computer using aninterpreter. Additional examples of computer code include, but are notlimited to, control signals, encrypted code, and compressed code.

In some variations, the systems and methods may be in communication withother computing devices (not shown) via, for example, one or morenetworks, each of which may be any type of network (e.g., wired network,wireless network). A wireless network may refer to any type of digitalnetwork that is not connected by cables of any kind. Examples ofwireless communication in a wireless network include, but are notlimited to cellular, radio, satellite, and microwave communication.However, a wireless network may connect to a wired network in order tointerface with the Internet, other carrier voice and data networks,business networks, and personal networks. A wired network is typicallycarried over copper twisted pair, coaxial cable and/or fiber opticcables. There are many different types of wired networks including widearea networks (WAN), metropolitan area networks (MAN), local areanetworks (LAN), Internet area networks (IAN), campus area networks(CAN), wireless personal area network (PAN) (e.g., Bluetooth, BluetoothLow Energy), global area networks (GAN), like the Internet, and virtualprivate networks (VPN). Hereinafter, network refers to any combinationof wireless, wired, public and private data networks that are typicallyinterconnected through the Internet, to provide a unified networking andinformation access system.

Cellular communication may encompass technologies such as GSM, PCS, CDMAor GPRS, W-CDMA, EDGE or CDMA2000, LTE, WiMAX, and 5G networkingstandards. Some wireless network deployments combine networks frommultiple cellular networks or use a mix of cellular, Wi-Fi, andsatellite communication. In some variations, the systems, devices, andmethods described herein may include a radiofrequency receiver,transmitter, and/or optical (e.g., infrared) receiver and transmitter tocommunicate with one or more devices and/or networks.

The specific examples and descriptions herein are exemplary in natureand variations may be developed by those skilled in the art based on thematerial taught herein without departing from the scope of the presentinvention, which is limited only by the attached claims.

1. A prosthesis, comprising: a first cylinder comprising a first cylinder port and a second cylinder port; a first piston slidable within the first cylinder; a fluid sump comprising a sump port, and a fluid circuit, comprising: a first fluid channel comprising a first channel inlet, a first channel outlet, and a unidirectional variable-resistance valve configured to set a variable resistance to fluid flow through the first fluid channel; a second fluid channel comprising a second channel inlet, a second channel outlet, and a second channel check valve; a third fluid channel comprising a third channel inlet, a third channel outlet, and a third channel check valve; a fourth fluid channel comprising a fourth channel inlet, a fourth channel outlet, and a fourth channel check valve; a fifth fluid channel comprising a fifth channel inlet, a fifth channel outlet, and a fifth channel check valve; a first intersection comprising the first channel inlet, the second channel outlet, and the fifth channel outlet; a second intersection comprising the first cylinder port, the second channel inlet, and the third channel outlet; a third intersection comprising the sump port, the third channel inlet, and the fourth channel inlet; and a fourth intersection comprising the second cylinder port, the fourth channel outlet, and the fifth channel inlet.
 2. The prosthesis of claim 1, further comprising an extension state during cylinder extension wherein the fluid circuit is configured to permit fluid flow along a third fluid path sequentially through the first cylinder port, the second channel check valve, the variable-resistance valve, the fourth channel check valve, and to the second cylinder port.
 3. The prosthesis of claim 2, wherein the extension state is further configured to: permit fluid flow along a fourth fluid path sequentially from the sump port to the fourth channel check valve; and resist fluid flow through the third channel check valve and the fifth channel check valve: and permit fluid flow simultaneously in the third and fourth fluid paths.
 4. The prosthesis of claim 1, further comprising a mechanical sensor, wherein a resistance of the variable-resistance valve is determined based upon input from the mechanical sensor.
 5. The prosthesis of claim 1, wherein the fluid circuit further comprises a three-way valve comprising a first valve port connected to the fluid sump at a second sump port, a second valve port connected to the second intersection, and a third valve port connected to the fourth intersection.
 6. The prosthesis of claim 5, further comprising a variable resistor located between the third valve port and the fourth intersection along a sixth fluid channel, the sixth fluid channel comprising a sixth channel inlet at the fourth intersection and a sixth channel outlet connected to the third valve port.
 7. The prosthesis of claim 6, wherein the variable resistor comprises a unidirectional variable resistor configured to permit flow from the fourth intersection to the third valve port.
 8. The prosthesis of claim 5, wherein the three-way valve is a normally open three-way valve and wherein the three-way valve is configured to permit fluid passage between the first, second, and third valve ports when open, and blocks fluid passage between the first, second, and third valve ports when closed.
 9. The prosthesis of claim 7, wherein the variable resistor blocks fluid flow from the third valve port to the fourth intersection regardless of whether the three-way valve is open or closed.
 10. The prosthesis of claim 9, further comprising a power-off flexion state during cylinder compression wherein the fluid circuit is configured to permit fluid flow along a fifth fluid path sequentially through the second cylinder port, the variable resistor, the third valve port, the second valve port, and to the first cylinder port and to permit fluid flow along a sixth fluid path from the first valve port to the fluid sump.
 11. The prosthesis of claim 9, further comprising a power-off extension state wherein the fluid circuit is configured to permit fluid flow along a seventh fluid path sequentially through the first cylinder port, the second valve port, the first valve port, the first sump port, the fourth fluid channel, and to the second cylinder port.
 12. The prosthesis of claim 1, wherein the variable resistance valve is a three-way spool valve and further comprises a secondary channel inlet.
 13. The prosthesis of claim 12, wherein the fluid circuit further comprises: a seventh fluid channel comprising a seventh channel inlet, a seventh channel outlet, and a seventh channel check valve, wherein the seventh channel inlet is connected to the first cylinder port or the second intersection; an eighth fluid channel comprising an eighth channel inlet, an eighth channel outlet, and a variable resistor; and a fifth intersection comprising the seventh fluid channel outlet, the eighth channel outlet and the secondary channel inlet of the three-way spool valve; wherein the first intersection further comprises the eighth channel inlet.
 14. The prosthesis of claim 13, further comprising a power-off flexion state during cylinder compression wherein the fluid circuit is configured to permit fluid flow along an eighth fluid path sequentially through the second cylinder port, the fifth fluid channel, the eighth fluid channel, the secondary channel inlet of the variable-resistance valve, the third fluid channel, and to the first cylinder port, and to permit fluid flow from the first channel outlet to the fluid sump.
 15. The prosthesis of claim 13, further comprising a power-off extension state during cylinder extension wherein the fluid circuit is configured to permit fluid flow along a ninth fluid path sequentially through the first cylinder port, the seventh fluid channel, the first channel inlet, the variable-resistance valve, the fourth fluid channel, and to the second cylinder port, and to permit a fluid flow from the fluid sump to the fourth fluid channel.
 16. The prosthesis of claim 12, wherein the three-way spool valve comprises a spring and is configured to normally permit fluid communication between the secondary channel inlet and the first channel outlet when the three-way spool valve is not powered.
 17. The prosthesis of claim 1, wherein the fluid sump comprises a spring-biased piston or a pneumatic piston.
 18. The prosthesis of claim 1, further comprising: an upper joint member coupled to the first piston; and a lower joint member coupled to the upper joint member and the first cylinder.
 19. A fluid circuit, comprising: a first fluid channel comprising a first channel inlet, a first channel outlet, and a unidirectional variable-resistance valve configured to set a variable resistance to flow through the first fluid channel; a second fluid channel comprising a second channel inlet, a second channel outlet, and a second channel check valve; a third fluid channel comprising a third channel inlet, a third channel outlet and a third channel check valve; a fourth fluid channel comprising a fourth channel inlet, a fourth channel outlet, and a fourth channel check valve; a fifth fluid channel comprising a fifth channel inlet, a fifth channel outlet and a fifth channel check valve; a first intersection comprising the first channel inlet, the second channel outlet, and the fifth channel outlet; a second intersection comprising a first bi-directional channel, the second channel inlet and the third channel outlet; a third intersection comprising a second bi-directional channel , the third channel inlet and the fourth channel inlet; and a fourth intersection comprising a third bi-directional channel, the fourth channel outlet and the fifth channel inlet.
 20. The fluid circuit of claim 19, further comprising a first state wherein the fluid circuit is configured to permit fluid flow along a first fluid path sequentially through the third bi-directional channel, the fifth channel check valve, the variable-resistance valve, the third channel check valve, and to the first directional channel.
 21. The fluid circuit of claim 20, wherein the first state is further configured to permit fluid flow along a second fluid path through the variable-resistance valve and to the second bi-directional channel.
 22. The fluid circuit of claim 20, wherein the first state is further configured to resist fluid flow through the second channel check valve and the fourth channel check valve.
 23. The fluid circuit of claim 20, wherein the first state is configured to permit fluid flow simultaneously in the first and second fluid paths.
 24. The fluid circuit of claim 19, further comprising a second state wherein the fluid circuit is configured to permit fluid flow along a third fluid path sequentially through the first bi-directional channel, the second channel check valve, the variable-resistance valve, the fourth channel check valve, and to the third bi-directional channel.
 25. The fluid circuit of claim 24, wherein the second state is further configured to permit fluid flow along a fourth fluid path sequentially through the second bi-directional channel and the fourth channel check valve.
 26. The fluid circuit of claim 24, wherein the second state is further configured to resist fluid flow through the third channel check valve and the fifth channel check valve.
 27. The fluid circuit of claim 24, wherein the second state is configured to permit fluid flow simultaneously along the third and fourth fluid paths.
 28. The fluid circuit of claim 19, further comprising a mechanical sensor and wherein a resistance of the variable-resistance valve is determined based upon input from the mechanical sensor.
 29. The fluid circuit of claim 19, wherein the variable-resistance valve is selected from the group consisting of a solenoid valve, a spool valve, and a voice coil valve.
 30. The fluid circuit of claim 19, wherein the fluid circuit further comprises a three-way valve, comprising a first valve port connected to the second bi-directional channel, a second valve port connected to the second intersection, and a third valve port connected to the fourth intersection.
 31. The fluid circuit of claim 30, further comprising a variable resistor located between the third valve port and the fourth intersection along a sixth fluid channel, the sixth fluid channel comprising a sixth channel inlet at the fourth intersection and a sixth channel outlet connected to the third valve port.
 32. The fluid circuit of claim 31, wherein the variable resistor is a unidirectional variable resistor configured to permit flow from the fourth intersection to the third valve port.
 33. The fluid circuit of claim 31, wherein the three-way valve is a normally open three-way valve.
 34. The fluid circuit of claim 31, wherein the three-way valve permits fluid passage between the first, second, and third valve ports when open, and blocks fluid passage between the first, second, and third valve ports when closed.
 35. The fluid circuit of claim 34, wherein the variable resistor blocks fluid flow from the third valve port to the fourth intersection regardless of whether the three-way valve is open or closed .
 36. The fluid circuit of claim 35, further comprising a third state wherein the fluid circuit is configured to permit fluid flow along a fifth fluid path sequentially through the third bi-directional channel, the variable resistor, the third valve port, the second valve port, and to the first bi-directional channel.
 37. The fluid circuit of claim 36, wherein the third state of the fluid circuit is further configured to permit a fluid flow along a sixth fluid path from the first valve port to the second bi-directional channel.
 38. The fluid circuit of claim 35, further comprising a power-off extension state wherein the fluid circuit is configured to permit fluid flow along a seventh fluid path sequentially through the first cylinder port, the second valve port, the first valve port, the fourth fluid channel, and to the second cylinder port. 